Add check for co-author email = author email

services/repository/contributors_graph.go

@@ -161,6 +161,10 @@ func getExtendedCommitStats(repo *git.Repository, revision string /*, limit int
 						break
 					}
 					coAuthorName, coAuthorEmail, err := util.ParseCommitTrailerValueWithAuthor(line)
+					if authorEmail == coAuthorEmail {
+						// Authors shouldn't be co-authors too.
+						continue
+					}
 					if err != nil {
 						continue
 					}

tests/gitea-repositories-meta/user2/repo2.git/refs/heads/branch-with-duplicated-co-author-entries

@@ -1 +1 @@
-79a64f10ca2ea21fa2a94102751f0dd9f2c15ce8
+f7eee4e802f39ec0dadc5f872c86d4ee440b741d