Correctly handle normalized tags

changelog.d/2529.change.rst

+Fixed an issue where version tags may be added multiple times

setuptools/command/egg_info.py

@@ -130,10 +130,12 @@ class InfoCommon:
         egg_info may be called more than once for a distribution,
         in which case the version string already contains all tags.
         """
-        return (
-            version if self.vtags and version.endswith(self.vtags)
-            else version + self.vtags
-        )
+        # Remove the tags if they exist. The tags maybe have been normalized
+        # (e.g. turning .dev into .dev0) so we can't just compare strings
+        base_version = parse_version(version).base_version
+
+        # Add the tags
+        return base_version + self.vtags
 
     def tags(self):
         version = ''