Gifts and personal at the same time?

Nope.

If you mean when you're buying a pack (like this), nope.

No, I mean 2 different games. So lets say if you buy them as a gift and check the box for putting it into your inventory.
Is it then possible to open games in your inventory and make them your own?

Buy them all as gifts and store in inventory, then activate the game you want from the inventory.

Actually it depends on the pack. In some cases you get extra copies of a certain game within a pack if you already own it.

EDIT: Nevermind. Yes, you can redeem stuff in your inventory that you purchased yourself.

thanks for the quick replys :D

no
you have do 2 purchases
and you can't split bundles