Can you use different magic bands on teh same trip? different colors/designs on teh same trip/day ? How do they know you are not "sharing" your band other than BiMetric Finger scans?
Poor Dave has 3 Purple Magic Bands\\Heres an outdated image with MB1s but it shows a guest with 3 MBs attached to the same person.
All your bands are linked to their owner in your MDE account. As long as they’re all active you can use any one (or color, lol) of your own bands to enter the park. They are basically clones of each other. You can swap amongst yourselves once you’re in the park if you want to use someone elses fp for a ride. We do it all the time. My daughter hates a lot of the rides we like. Plus, my kids seem to lose a band every trip. Saves going to guest services for a replacement. Last trip we had roughly 12 magicbands with us for 4 people
WE always have multiple bands per person. My sister who was on her first trip just grabbed a pink band when leaving the room not realizing it wasn’t hers. We were stopped on our way in to Epcot because it was my band and I had already scanned into the park. THey looked up our MDE and asked who she was on our reservation and gave her a card to use for the day no problem.
I could have written your post except for the part about 12 MBs (I carry one spare for each person in my bag). If we had 3 MBs each, I guarantee that on the day when we had a PPO breakfast ADR and plans for RD we'd arrive at the tap styles to find that someone had an MB that wasn't theirs.
Being multiple MBs with care!
The center section of the band has the RFID chip--that's the part that is keyed to a particular person on MDE--has your ticket, FP+, dining plan entitlements, room key, etc. These days you're able to remove the center part with a small screwdriver (maybe an eyeglasses one?) and change bands amongst your party--keeping your center piece. I plan it out ahead of time when I'm ordering them, so we then have a different colored band from the center. (Say DD wants a purple band and green center...I order her a green one and myself the purple and then we swap bands.)
As others have said, if you've been to Disney before, you can reuse your previous Magicbands--I think the RFID chip is good for up to 2 yrs.