Cross-posts appear differently depending on your client. I'm using Lemmy as my web client and Boost on Android. Both of them show cross-posts as independent posts. The only difference is that there's a little marker to tell you that it's cross-posted. I think on Piefed, they aggregate the comments from each cross-post. I don't know what they do with the top level post.

You should also know that upvotes and downvotes are public on this platform. It's not a good look when you upvote your own comments like that.