Because the Eidolon has to be at least one size category larger than it's target to grapple in the first place, my GM houseruled I could grapple one target per claw attack (fluff-wise, it's more of a 'stand on' than a 'grapple'). I can't release and grapple the same target more than once, but sinse my Synthesist is the party Tank, I spend a lot of my timeleapingpouncing into the middle of groups.