If you submit a link that someone else already posted, it just counts your "submission" as an upvote on the older post.

If you submit a duplicate URL, HN "accepts" it then redirects you to the earlier posting.

That's probably what happened.

Did they actually change the author of the post? I don't see it in your submission history anymore.

I submitted the post, but the title was changed from

> Spotify responds to "Decide which init system to default to in Debian"

I did mistakenly link to a dynamic resource, though.