Preserve the addedTimestamp during import

client/src/main/java/ctbrec/ui/tabs/recorded/AbstractRecordedModelsTab.java

@@ -249,7 +249,9 @@ public abstract class AbstractRecordedModelsTab extends Tab implements TabSelect
             protected Void call() {
                 for (Model model : models) {
                     try {
+                        Instant addedTimestamp = model.getAddedTimestamp(); // preserve old addedTimestamp
                         recorder.addModel(model);
+                        model.setAddedTimestamp(addedTimestamp); // restore old addedTimestamp
                     } catch (Exception e) {
                         log.error("Couldn't add model to recording list", e);
                     }