First of all: Thanks for an amazing app!
When opening a comment through the inbox, then pressing back afterwards makes all comments show up twice in the list. Repeating this will make them show thrice.
Exiting and reopening the inbox solves the issue.
When I upvote a comment then press back it shows both ‘versions’ of the message. A screenshot of the Connect for Lemmy app, showing the inbox screen with the same comment shown five times.  The comment, by a user named Josh, says "@cuteblooded @troll just keep posting and follow some interesting people you'll get it