Since you have the yarn for the second one, you wouldn't have to frog the first one before you start again. If I have something too big or too small, I like to leave it until I've gotten the new one going for comparison to make sure that I'm making the size difference I want.
Cheating is an option. . . . Cheaters never win and winners never cheat, but smart knitters who want to retain an iota of sanity do, cheerfully. ~~Kory Stamper