Second part-time job advice?

I was on a job hunt and applied to many stores in the mall by my house. I immediately got a job interview and was hired within two weeks. I had another interview and since I wasn't getting that many hours at the first one I decided to go. I ended up getting the second job as well and decided to take it on because I have had more than two jobs at once. So I haven't started at the second one yet, but I did sign papers and get all the information. Then I happened to get a lot more hours at my first job. I only have about a month and a half until school starts again, when I plan on leaving both (ONLY because my school schedule requires a lot of my time and it will be difficult to have one job, let alone two). Also, as a side note: I do enjoy both jobs and would love to keep both if it worked out that way.

So what I'm asking is should I just try to stick with both jobs until summer is over, or should I quit the second one? Should I make my schedule really specific so I can avoid any conflicts, and say I've gotten a good offer to do something that would further me and be beneficial for my college program? HELP!