A312 It's not entirely clear, but logically three. Of course, you're not getting thrice restrained, but it's still three nets on you. The restrained condition might not stack, but you're being restrained by three separate sources, so you'll have to break all three. See also a similarly kinda vague situation, being grappled by multiple enemies. Logically, you again have to deal with each one separately, not break all grapples at once.