Yes there are two seperate shoulder bells, one with the swoop and the other without. Mike is right about the inconsistancy of the suits too. From what I have read, the troopers had to grab what they could before filming and the results were troopers wearing stuff on the wrong arms, legs or both. From looking at both bells side by side, the strips both seem to slope backwards (opposite from each other) so it looks as though the swoop is designed for the left arm while the non-swoop is for the right. That of course is purely speculation on my part, but there is definately two different bells.
Mike, the sandtroopers did have the swoop. I'll see if I can find a decent pic.