Transferring saves was confirmed to auto pop trophies you've already completed.
Uncharted: Legacy of Thieves Collection Trophies
1 Platinum • 4 Gold • 20 Silver • 76 Bronze
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I'm not exactly sure what happened here but it's a weird structure out of the ordinary for a Trophy list (Especially first-party). All of Uncharted 4 makes up the majority of the list outside of 1 trophy called "Don't Ruin The Moment" which is a Gold for getting all TLL trophies. The TLL trophies themselves are from the retail game but are under a DLC tab thus no additional platinum.
While the game not having two platinums is one thing (It happens). It seems a bit weird to tie the platinum completion to both games when there's only one on offer. Why it wasn't two platinum or just regulating TLL to a DLC slot is anyone's guess. I do believe this makes it the record for "DLC" with the most amount of trophies tied to it though.
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Don't let this turn you off from playing the games, however. I more wanted to make this thread as a PSA for anyone who had a bit of unfinished business on the PS4 versions of 4 & TLL (Like I do). Might be worth mopping up anything you missed there so you can transfer that save over and get a total of 3 platinums out of all of this.