I can enter life is strange giveaways and i already got it

Most DLC's have the same issue. Probably because one game ID differs from what we are entering. Your best solution is to just hide every DLC you own that you see giving away here.

DLCs don't report ownership properly through the Steam API, meaning any DLC or package including DLCs will not show up as properly owned. As such, SG users need to be careful to check if they already own any content related to DLCs, and rely on the manual hide function to avoid entering for owned content.

Conversely, some packages don't properly list DLCs included within them, which can sometimes lock out people who already own all base games within the package, as SG believes they already own all the content.

who knows, just hide it and forget about it. ¯\_(ツ)_/¯