Got one good score and one bad score... what should I do?

So I have taken 2 subject tests because some schools recommend 2 subject tests (I wanna apply to UC Berkeley, UCLA Stanford, and other selective colleges). I got a 750 in US history which is good but also 650 in Biology. I was wondering, since it’s only recommended subject tests should I use score choice to send only one to those colleges that allow score choice? But then again it is only one test, wouldn’t that be really random when other people are taking 2 or 3 subject tests, will that really help me?

I wanna apply to selective colleges, is a 650 gonna hurt my chances? Also, it’s better if you apply early to some colleges like Stanford, will I have time to retake the bio test, considering I still have to retake the SAT.