Can i install two crossfire bridges on ati 5770?

Don't ever install two bridges on two cards! AMD doesn't recommend using two bridges...there's no improvement in performancee and sometimes there's signal intereference. In the earlier generations of crossfire like on Radeon HD 2900 and HD 3000 series you would need two ribbon connectors...but not on current generation cards. You only need one bridge for current genaration cards. The purpose of the two bridge ends on the cards is to bridge more than two cards...like 3 or 4 graphics cards...