UploadBase::checkAgainstExistingDupes finds duplicate files with the same content (by hash), but omits files that have the same name as the one being uploaded.
This may make sense for local files (same filenames will already be reported as 'exists' warning, and 'nochange' if the content is the same)
'exists' & 'nochange' are only checked on local repositories, though.
For matches in foreign repositories, you won't get these warnings. Duplicates are still treated the same, though: if they have the same filename, they'll be filtered out.
As a result, a same name + same content upload of a file in a foreign repo will not generate any warnings.
I suggest we don't filter out same-name duplicates in UploadBase::checkAgainstExistingDupes when it's on a foreign repo.