sixth form

Hi, i would like to know if i can confirm more then one sixth form college ?

I wouldn't recommend it, why?
If you explain a bit more I can try to advise

Because i sent emails to sixth forms and see if they will accept me, at the mean time i want to confirm a college so i have a back up

Ah, confirm a college and then if you receive an offer to study at another one, accept then ring up the previous college immediately and explain that you've had an offer to study elsewhere and you've decided to accept that offer and so won't be enrolling with them at the start of term sorry.
That sound okay?