Im buying the thq compilation on steam, is it possible to gift to other people games I already have within this compilation?
Here's Valve's official page on extra copies: https://support.steampowered.com/kb_article.php?ref=4502-TPJL-2656
Both in past experience and based on this, no you don't get extra copies.
i have purchased a few bundles that have included games I already have and have never received an extra copy of the games i already have that I could then give away. Also, if you buy a bundle "as a gift" it then goes into your inventory as the bundle, not as individual games. so you can't get around it that way, either.