ask for help! Thanks

I got a H-1 offer yesterday and was required to say YES or No within one week. Meanwhile, I will have an interview for another H-1 in April. If I say YES and get H-1 in two weeks in express way, then I find that another position is suitable for me after interview in April. Can I apply H-1 for this position? Does previous application and approval affect this H-1 application? Thanks for help.