They can put the same game on all of your bands,(and in the early stages they did this automatically if you didn’t request separate games), or....the way out family of 4 does it....DH and DD have one game on their magic bands. DS and I have a separate, 2nd game on our magic bands. Both kids like to play....esp. as they hit the preteen stage, so this worked well for us. When my DD was younger, she would tire of it faster than big brother so she and DH would head to resort pool while DS and I (really DS....I just tag along) stay and play several more portals on his game. You will split up most of the time if you choose to have two games because games send you to different portals even when you start in the same land.
Tip: keep your magic bands for return trips. We have played the same game across several years which allowed both my kids to eventually defeat the final villain and earn the bonus card packs. They also get to sign the Master Sorcerer (or something like that) book. They can transfer your game to your new magic band on future trips...but only if you have your old magic band from which to transfer it.