As long as you weren't initiated by the first fraternity, then technically yes, you can pledge another. However, some chapters may not look favorably upon someone who moves from one group to another, so you may encounter some difficulty with that. Things like this can very from campus to campus.
I'd recommend using the
search feature and/or checking out the
Recruitment forum for further information, as I'm sure you'll find others have asked this same question previously to which numerous replies have been given. In the interest of not duplicating those threads, this one is now closed.
Best of luck to you.