Applying for my first job?

It's the summer and school's almost out. I was thinking of applying at both F.Y.E. and Regal Cinemas. I was wondering how the process of getting a job usually works, since this is my first time applying for a job and what not. I'm 16, turning 17 this July so I'm of legal age to work. If I applied at both, and say they both were interested in me but I could only pick one, would that hurt the chances of me working at the other place in the future (say maybe next summer)? or do they just throw out old applications? or does it depend on the company? Also I would love any first job advice. Thanks!