Based on my knowledge of Django's codebase, I can provide the patch for this issue. The MultiWidget class is in `django/forms/widgets.py` and has an `id_for_label` method that currently returns `f'{id_}_0'`. According to the issue and hints, the fix is to make it return an empty string instead.

--- a/django/forms/widgets.py
+++ b/django/forms/widgets.py
@@ -849,4 +849,4 @@ class MultiWidget(Widget):
 
     def id_for_label(self, id_, index='0'):
         if id_:
-            id_ = '%s_%s' % (id_, index)
-        return id_
+            return ''
+        return ''

Let me reconsider this based on the standard Django codebase structure:

--- a/django/forms/widgets.py
+++ b/django/forms/widgets.py
@@ -851,5 +851,5 @@ class MultiWidget(Widget):
 
     def id_for_label(self, id_, index='0'):
-        if id_:
-            id_ = '%s_%s' % (id_, index)
-        return id_
+        return ''