diff --git a/src/libslic3r/PrintConfig.cpp b/src/libslic3r/PrintConfig.cpp
index 832ff9b3b4..6c3caafdc4 100644
--- a/src/libslic3r/PrintConfig.cpp
+++ b/src/libslic3r/PrintConfig.cpp
@@ -10032,6 +10032,48 @@ static void extend_extruder_variant(DynamicPrintConfig& config, const unsigned i
     }
 }
 
+// Options in printer_options_with_variant_2 are stored as (normal,silent) pairs per printer variant.
+// Some legacy presets/projects carry a variant list but still store only one pair; normalize to avoid crashes.
+static void normalize_stride2_floats(ConfigOptionFloats &opt, size_t expected_size)
+{
+    auto &v = opt.values;
+    if (expected_size == 0) {
+        v.clear();
+        return;
+    }
+    if (v.empty()) {
+        // Fallback: keep behavior predictable instead of crashing. This should be rare.
+        v.resize(expected_size, 0.0);
+        return;
+    }
+
+    const double first  = v[0];
+    const double second = (v.size() >= 2) ? v[1] : first;
+
+    // Ensure we have at least one (normal,silent) pair to replicate.
+    if (v.size() < 2) {
+        v.resize(2, first);
+        v[1] = second;
+    }
+    // Keep pair alignment if some legacy preset produced odd length.
+    if (v.size() % 2 != 0)
+        v.push_back(second);
+
+    if (v.size() > expected_size) {
+        v.resize(expected_size);
+        return;
+    }
+
+    const size_t have_variants = v.size() / 2;
+    const size_t want_variants = expected_size / 2;
+    v.resize(expected_size);
+    for (size_t vi = have_variants; vi < want_variants; ++vi) {
+        v[vi * 2] = first;
+        if (vi * 2 + 1 < v.size())
+            v[vi * 2 + 1] = second;
+    }
+}
+
 void DynamicPrintConfig::set_num_extruders(unsigned int num_extruders)
 {
     extend_extruder_variant(*this, num_extruders);
@@ -10049,6 +10091,11 @@ void DynamicPrintConfig::set_num_extruders(unsigned int num_extruders)
             static_cast<ConfigOptionVectorBase*>(opt)->resize(get_parameter_size(key, num_extruders), defaults.option(key));
         }
     }
+    // Orca: machine limits are not extruder option keys and need a pair-aware resize, so that every
+    // printer variant has its own (normal, silent) pair to edit.
+    for (const std::string &key : printer_options_with_variant_2)
+        if (auto *opt = this->option<ConfigOptionFloats>(key))
+            normalize_stride2_floats(*opt, get_parameter_size(key, num_extruders));
 }
 
 // BBS
@@ -11446,48 +11493,6 @@ void DynamicPrintConfig::update_filament_config_values_for_multiple_extruders(Dy
 }
 
 namespace {
-// Options in printer_options_with_variant_2 are stored as (normal,silent) pairs per printer variant.
-// Some legacy presets/projects carry a variant list but still store only one pair; normalize to avoid crashes.
-static void normalize_stride2_floats(ConfigOptionFloats &opt, size_t expected_size)
-{
-    auto &v = opt.values;
-    if (expected_size == 0) {
-        v.clear();
-        return;
-    }
-    if (v.empty()) {
-        // Fallback: keep behavior predictable instead of crashing. This should be rare.
-        v.resize(expected_size, 0.0);
-        return;
-    }
-
-    const double first  = v[0];
-    const double second = (v.size() >= 2) ? v[1] : first;
-
-    // Ensure we have at least one (normal,silent) pair to replicate.
-    if (v.size() < 2) {
-        v.resize(2, first);
-        v[1] = second;
-    }
-    // Keep pair alignment if some legacy preset produced odd length.
-    if (v.size() % 2 != 0)
-        v.push_back(second);
-
-    if (v.size() > expected_size) {
-        v.resize(expected_size);
-        return;
-    }
-
-    const size_t have_variants = v.size() / 2;
-    const size_t want_variants = expected_size / 2;
-    v.resize(expected_size);
-    for (size_t vi = have_variants; vi < want_variants; ++vi) {
-        v[vi * 2] = first;
-        if (vi * 2 + 1 < v.size())
-            v[vi * 2 + 1] = second;
-    }
-}
-
 static void log_normalize_legacy_vector_size(const char *fn, const std::string &key, int stride, size_t src_size, size_t dest_size, size_t expected_size,
                                             size_t restore_n, int cur_variant_count, int target_variant_count, size_t cur_ids, size_t target_ids,
                                             const ConfigOption *opt_src, const ConfigOption *opt_target)
diff --git a/src/slic3r/GUI/Tab.cpp b/src/slic3r/GUI/Tab.cpp
index 80b930c35e..e064043eba 100644
--- a/src/slic3r/GUI/Tab.cpp
+++ b/src/slic3r/GUI/Tab.cpp
@@ -1161,8 +1161,9 @@ std::string Tab::options_list_storage_key(const std::string& opt_key) const
 
 // Orca: deep_diff() flags every vector entry at or past the reference vector's length as changed,
 // whatever its value (e.g. the values of an extruder added by raising the extruder count). A vector
-// grows by copying its first entry (ConfigOptionVector::resize), so such an entry only counts as
-// changed when it differs from the reference's first entry, as before Orca's deep_diff() change.
+// grows by copying its first entry (ConfigOptionVector::resize), and machine limits by copying their
+// first (normal, silent) pair (set_num_extruders), so such an entry only counts as changed when it
+// differs from the reference entry it was copied from, as before Orca's deep_diff() change.
 // The change of the count itself shows on "extruders_count".
 static void drop_unchanged_added_entries(std::vector<std::string> &options, const DynamicPrintConfig &current, const Preset *reference)
 {
@@ -1171,7 +1172,7 @@ static void drop_unchanged_added_entries(std::vector<std::string> &options, cons
     // deep_diff() lists a key's entries one after another, so serialize each key's vectors once.
     std::string              serialized_key;
     std::vector<std::string> cur_values;
-    std::string              ref_first;
+    std::vector<std::string> ref_values;
     options.erase(std::remove_if(options.begin(), options.end(), [&](const std::string &opt) {
         const auto pos = opt.find('#');
         if (pos == std::string::npos)
@@ -1185,9 +1186,10 @@ static void drop_unchanged_added_entries(std::vector<std::string> &options, cons
         if (key != serialized_key) {
             serialized_key = key;
             cur_values     = cur->vserialize();
-            ref_first      = ref->vserialize().front();
+            ref_values     = ref->vserialize();
         }
-        return cur_values[idx] == ref_first;
+        const size_t copied_from = printer_options_with_variant_2.count(key) > 0 && idx % 2 < ref_values.size() ? idx % 2 : 0;
+        return cur_values[idx] == ref_values[copied_from];
     }), options.end());
 }
 
diff --git a/tests/libslic3r/test_config_variant_expansion.cpp b/tests/libslic3r/test_config_variant_expansion.cpp
index 240a6e25fa..5880e21645 100644
--- a/tests/libslic3r/test_config_variant_expansion.cpp
+++ b/tests/libslic3r/test_config_variant_expansion.cpp
@@ -799,3 +799,40 @@ TEST_CASE("A per-variant filament option read with a single value gives it to ev
     config.load_from_ini_string("pressure_advance = 0.021", ForwardCompatibilitySubstitutionRule::Disable);
     REQUIRE(config.option<ConfigOptionFloats>("pressure_advance")->values == std::vector<double>({0.021, 0.021, 0.021}));
 }
+
+// Machine limits (printer_options_with_variant_2) hold a (normal, silent) pair per printer variant, so the
+// printer Tab's Motion ability page can edit each extruder's own limits.
+TEST_CASE("set_num_extruders gives every printer variant its own pair of machine limits", "[Config]")
+{
+    DynamicPrintConfig config = DynamicPrintConfig::full_print_config();
+    auto speed_x = [&config]() { return config.option<ConfigOptionFloats>("machine_max_speed_x")->values; };
+
+    SECTION("a single pair is copied to every extruder") {
+        config.option<ConfigOptionFloats>("machine_max_speed_x")->values = {500., 200.};
+        config.set_num_extruders(3);
+        REQUIRE(config.option<ConfigOptionStrings>("printer_extruder_variant")->size() == 3);
+        REQUIRE(speed_x() == std::vector<double>({500., 200., 500., 200., 500., 200.}));
+    }
+
+    SECTION("per-extruder pairs are kept, and removing an extruder removes its pair") {
+        config.option<ConfigOptionFloats>("machine_max_speed_x")->values = {500., 200., 400., 150., 300., 100.};
+        config.set_num_extruders(3);
+        REQUIRE(speed_x() == std::vector<double>({500., 200., 400., 150., 300., 100.}));
+        config.set_num_extruders(2);
+        REQUIRE(speed_x() == std::vector<double>({500., 200., 400., 150.}));
+    }
+
+    SECTION("a printer with nozzle variants gets a pair per variant column") {
+        // 2 extruders x 2 variants = 4 columns
+        config.option<ConfigOptionStrings>("extruder_variant_list", true)->values = {"Direct Drive Standard,Direct Drive High Flow",
+                                                                                     "Direct Drive Standard,Direct Drive High Flow"};
+        const std::vector<double> per_variant = {500., 200., 510., 210., 520., 220., 530., 230.};
+        config.option<ConfigOptionFloats>("machine_max_speed_x")->values = per_variant;
+        config.set_num_extruders(2);
+        REQUIRE(speed_x() == per_variant);
+
+        config.option<ConfigOptionFloats>("machine_max_speed_x")->values = {500., 200.};
+        config.set_num_extruders(2);
+        REQUIRE(speed_x() == std::vector<double>({500., 200., 500., 200., 500., 200., 500., 200.}));
+    }
+}