I deleted a post after I accidentally posted it twice from two different accounts (on sopuli and fmhy).
The deleted post was as I expected gone from my sopuli account, but from my fmhy account I can see that both posts are still up. People can still see and comment on both. I just can no longer see it.
Pretty sure it has to do with the content not being updated on that instance then. It should be deleted but I can imagine it taking time for instances to instances.