This is an old post, but I'm seeing the same issue @[email protected]
In my case it is self-hosted with docker, here is an example: https://lemmy.ca/post/39867153
Interestingly, sorting by new in the community only brings up one copy of the post, but both posts show up in the UI under 'crosspost', as well as in the user's post history: https://lemmy.ca/c/vancouver?dataType=Post&sort=New
