[quote=92013]I know that, but it is possibe to get to the regular raspbian and still have RetroPie on it?[/quote]

RetroPie has regular Raspbian, just with a few packages uninstalled (that you’re free to re-install and maybe don’t need anyways). It would help if you actually said why you want to dual boot.

But yeah there’s plenty of info on dual booting a pi, and from your first comment it sounds like you’ve already done it in the past:
https://www.google.com/search?q=dual+boot+raspberry+pi&btnG=–%3E&gws_rd=ssl