Question about trophy syncing with cross-gen titles

[machaesthetic]

So I logged into my PS3 for the first time in a few years and when I checked my trophy collection I noticed that even after it synced, that there were titles (such as Spelunky and Hotline Miami) that I originally started on PS3 and later 100%'ed on PS4, however these games only showed the percentage from just the trophies earned on the PS3 version. It was only after I synced by clicking on my profile (rather than my trophy collection) that it updated the PS3 trophy lists with what I had earned from PS4 (although you can only view PS4-only trophy lists when comparing lists, and not from your trophy collection). 

 

My question though is what would happen if you had earned the same trophy from a game on both platforms? Would it be the earliest timestamp or the earliest synced trophy that would appear on your list? Or could it possibly even change your timestamp if you synced late? Like for example if I had earned some trophies on my PS3 for a PS3/PS4 crossgen game in 2014, but either hadn't or only partially synced them, but then I later 100%'ed the game on PS4, what would happen with the list and the timestamps for those trophies earned on PS3? I guess alternatively, even though PS4 has auto-sync regularly, what if you earned a certain trophy on PS4, didn't sync it, then played the same game on PS3 and earned that trophy on PS3 then synced it. What would happen with that trophy when you synced the PS4 version?

 

Just curious because it seems like it could lead to potential problems, possibly even what appears to be edited timestamps, although I've never really seen anyone mention it and can't find any answer when I looked online.