Can the same name be on two room reservations?

Totally doable, so long as you're not going over room capacity. I do it all the time; usually I get a studio for myself and then another room (sometimes a studio, sometimes a one or two BR, depending on the size of the travel party) for my guests....probably would help to use a "name variation"--for example, if your DD and DSIL are John A and Mary B Smith, you might want to list them on your reservation as JA and MB Smith....cuts down on the possibility of confusion....but even if you don't do it that way, you just go to the front desk and they'll make the necessary adjustments, give you key cards (if you want them), etc. Your DD and DSIL can have their magic bands adjusted when they check out of their studio (but you'll need to get them key cards if you want them to have access to your room while they're in their studio) one magic band can't accommodate access to two rooms...the only issue I've ever had was when I had a 2-BR for a large family party and a studio for myself (only so much togetherness is a good thing for me), and I had to have something I'd forgotten to bring w/me delivered to Kidani....the Kidani people "assigned" the delivery to the 2-BR rather than to my studio, but it took only about 2 minutes to get that sorted out....good luck....

Thank you both for the info. I won’t bother with key cards for them but just have them get their magic bands adjusted when they check out of the studio.

They probably will be going to the parks so that’s what I was concerned about, I want them on our two bedroom reservation. I was going to do what dmkedm suggested and list them by initials on our reservation. At the end of the studio stay then they can go to the front desk with their magic bands and get access to our room put on their bands. Hopefully that will work.

Do it the other way around if they aren't onsite. They'll lose privileges of being onsite if the tickets aren't linked properly. You can add them to your room if you like at the end but make sure they are properly added to your room.

That’s what I would do, yes. 

But do check your DVC account after to make sure the points are still OK. And call Member Services there & then if  there’s anything amiss. 

We ran into a somewhat similar situation with our May Treehouse vacation. DH's brother is down with his in-laws April 30 to May 5 so we invited BIL and SIL to join us in the Treehouses from May 5 to May 9. They accepted and we added them to our Treehouse. When I was looking for airfare I found that if we moved to May 4 we could fly on points. So we extended the Treehouse vacation from May 4 to 9. BIL mentioned that when I did that his MDE began to look incomplete. BIL called last week to get a promotional discounted package for his Port Orleans stay and CS told him he could not overlap his vacations. So I had to call and take them off of the Treehouses. MS told me to ask at SSR when we check in on May 4 if he's going to have a problem having his luggage moved on May 5. Something tells me I'll be hauling my giggly posterior over to SSR to add him back onto the reservation on the 5th. Luckily they no longer need park reservations. Hopefully it won't effect any of their dinner reservations.