diff --git a/src/libslic3r/GCode.hpp b/src/libslic3r/GCode.hpp
index 68bb85a98..497dc8c71 100644
--- a/src/libslic3r/GCode.hpp
+++ b/src/libslic3r/GCode.hpp
@@ -362,12 +362,11 @@ protected:
     bool                                m_second_layer_things_done;
     // Index of a last object copy extruded.
     std::pair<const PrintObject*, Point> m_last_obj_copy;
-    /* Extensions for colorprint - now it's not a just color_print_heights, 
-     * there can be some custom gcode.
-     * Updated before the export and erased during the process,
-     * so no toolchange occurs twice.
-     * */
-    std::vector<Model::CustomGCode> m_custom_gcode_per_print_z;
+    // Extensions for colorprint - now it's not a just color_print_heights,
+    // there can be some custom gcode.
+    // Updated before the export and erased during the process,
+    // so no toolchange occurs twice.
+    std::vector<Model::CustomGCode> 	m_custom_gcode_per_print_z;
 
     // Time estimators
     GCodeTimeEstimator m_normal_time_estimator;
diff --git a/src/libslic3r/Model.cpp b/src/libslic3r/Model.cpp
index 516733708..96a32680e 100644
--- a/src/libslic3r/Model.cpp
+++ b/src/libslic3r/Model.cpp
@@ -66,7 +66,7 @@ Model& Model::assign_copy(Model &&rhs)
     rhs.objects.clear();
 
     // copy custom code per height
-    this->custom_gcode_per_print_z = rhs.custom_gcode_per_print_z;
+    this->custom_gcode_per_print_z = std::move(rhs.custom_gcode_per_print_z);
     return *this;
 }
 
@@ -1946,25 +1946,23 @@ extern bool model_has_advanced_features(const Model &model)
 
 extern void update_custom_gcode_per_print_z_from_config(std::vector<Model::CustomGCode>& custom_gcode_per_print_z, DynamicPrintConfig* config)
 {
-    if (!config->has("colorprint_heights"))
+	auto *colorprint_heights = config->option<ConfigOptionFloats>("colorprint_heights");
+    if (colorprint_heights == nullptr)
         return;
 
-    const std::vector<std::string>& colors = GCodePreviewData::ColorPrintColors();
-
-    const auto& colorprint_values = config->option<ConfigOptionFloats>("colorprint_heights")->values;
-    
-    if (!colorprint_values.empty())
-    {
+	if (custom_gcode_per_print_z.empty() && ! colorprint_heights->values.empty()) {
+		// Convert the old colorprint_heighs only if there is no equivalent data in a new format.
+	    const std::vector<std::string>& colors = GCodePreviewData::ColorPrintColors();
+	    const auto& colorprint_values = colorprint_heights->values;
         custom_gcode_per_print_z.clear();
         custom_gcode_per_print_z.reserve(colorprint_values.size());
         int i = 0;
         for (auto val : colorprint_values)
             custom_gcode_per_print_z.emplace_back(Model::CustomGCode{ val, ColorChangeCode, 1, colors[(++i)%7] });
-    }
+	}
 
-    /* There is one and only place this configuration option is used now.
-     * It wouldn't be used in the future, so erase it.
-     * */
+	// The "colorprint_heights" config value has been deprecated. At this point of time it has been converted
+	// to a new format and therefore it shall be erased.
     config->erase("colorprint_heights");
 }
 
diff --git a/src/libslic3r/Model.hpp b/src/libslic3r/Model.hpp
index c5a992e49..44f5049c9 100644
--- a/src/libslic3r/Model.hpp
+++ b/src/libslic3r/Model.hpp
@@ -755,21 +755,15 @@ public:
     // Extensions for color print
     struct CustomGCode
     {
-        bool operator<(const CustomGCode& other) const { return other.print_z > this->print_z; }
-        bool operator==(const CustomGCode& other) const
+        bool operator<(const CustomGCode& rhs) const { return this->print_z < rhs.print_z; }
+        bool operator==(const CustomGCode& rhs) const
         {
-            return (other.print_z   == this->print_z    ) && 
-                   (other.gcode     == this->gcode      ) && 
-                   (other.extruder  == this->extruder   ) && 
-                   (other.color     == this->color      );
-        }
-        bool operator!=(const CustomGCode& other) const
-        {
-            return (other.print_z   != this->print_z    ) || 
-                   (other.gcode     != this->gcode      ) || 
-                   (other.extruder  != this->extruder   ) || 
-                   (other.color     != this->color      );
+            return (rhs.print_z   == this->print_z    ) && 
+                   (rhs.gcode     == this->gcode      ) && 
+                   (rhs.extruder  == this->extruder   ) && 
+                   (rhs.color     == this->color      );
         }
+        bool operator!=(const CustomGCode& rhs) const { return ! (*this == rhs); }
         
         double      print_z;
         std::string gcode;
@@ -880,9 +874,9 @@ extern bool model_volume_list_changed(const ModelObject &model_object_old, const
 extern bool model_has_multi_part_objects(const Model &model);
 // If the model has advanced features, then it cannot be processed in simple mode.
 extern bool model_has_advanced_features(const Model &model);
-/* If loaded configuration has a "colorprint_heights" option (if it was imported from older Slicer), 
- * then model.custom_gcode_per_print_z should be updated considering this option
- * */
+// If loaded configuration has a "colorprint_heights" option (if it was imported from older Slicer), 
+// and if model.custom_gcode_per_print_z is empty (there is no color print data available in a new format
+// then model.custom_gcode_per_print_z should be updated considering this option.
 extern void update_custom_gcode_per_print_z_from_config(std::vector<Model::CustomGCode>& custom_gcode_per_print_z, DynamicPrintConfig* config);
 
 #ifndef NDEBUG