I added a comment with links to two attached sound files. These had the same name but were two different versions.
After posting the comment and following the links in the comment, they both played the same file. I repeated this again, thinking I screwed up, to the same end. Both files are attached, and when opened via the attachments panel, they both play the correct version.
The solution would be to either handle duplicate filenames nicely (maybe variant tags, <non-unique-name>_a.ogg <non-unique-name>_b.ogg), or enforce unique filenames for attachments.