The Witcher 3: Wild Hunt is a phenomenal game that you must play if you haven't already, but if you have played it there's a great reason to replay it now especially if you're an achievement hunter! Today marks the release for The Witcher 3: Wild Hunt Complete Edition which includes the main game and all of the excellent DLC. Most of the times when these re-releases happen, Xbox or PlayStation just reuse the same achievement list and don't have it listed twice on their database.
However, every once and a while a developer will release a game of the year edition or bundle and they'll create a secondary achievement list which includes the same list of achievements except you can earn them twice if you buy both versions of the game. The Witcher 3 is one of those games! The achievement lists are identical and total up to 2000 gamerscore (4000 if you get both editions of the game). You can view the achievement list for the re-release here if you wish.