Fix duplication of fields in form layout

CHANGELOG.rst

@@ -13,6 +13,7 @@ Fixed
 ~~~~~
 
 * Fix creation on email addresses
+* Fix duplication of form fields in layout
 
 `1.1`_
 ----------

aleksis/apps/paweljong/forms.py

@@ -300,15 +300,18 @@ class RegisterEventAdditional(ExtensibleForm):
     def __init__(self, event, *args, **kwargs):
         super().__init__(*args, **kwargs)
 
+        self.__class__.layout_filled = getattr(self.__class__, "layout_filled", False)
+
         for field in event.linked_group.additional_fields.all():
             field_instance = getattr(fields, field.field_type)(
                 required=field.required,
                 help_text=field.help_text,
             )
             self.fields[field.title] = field_instance
-            node = Fieldset(f"{field.title}", f"{field.title}")
-            self.add_node_to_layout(node)
-
+            if not self.layout_filled:
+                node = Fieldset(f"{field.title}", f"{field.title}")
+                self.add_node_to_layout(node)
+        self.__class__.layout_filled = True
 
 class RegisterEventFinancial(ExtensibleForm):
     """Form to register for an event."""