Fixed #1672

core/src/mindustry/ui/dialogs/SchematicsDialog.java

@@ -90,6 +90,13 @@ public class SchematicsDialog extends FloatingDialog{
 
                             buttons.addImageButton(Icon.pencil, style, () -> {
                                 ui.showTextInput("$schematic.rename", "$name", s.name(), res -> {
+                                    Schematic replacement = schematics.all().find(other -> other.name().equals(res) && other != s);
+                                    if(replacement != null){
+                                        //renaming to an existing schematic is not allowed, as it is not clear how the tags would be merged, and which one should be removed
+                                        ui.showErrorMessage("$schematic.exists");
+                                        return;
+                                    }
+
                                     s.tags.put("name", res);
                                     s.save();
                                     rebuildPane[0].run();