I just went through this today. I was able to get air into the caliper to pop one out, I used a piece of cardboard between the two with a rag around it to keep it from shooting off.
What to do with the second one, though? Well, the key was to secure one with some clamps and use enough air to get the other out far enough that it could be popped out using the lip for the dust covers.
Yes, it’s loud, and not to mention that atomized brake fluid goes everywhere. So, be very careful and make sure you use all the protection, and something between the pistons to absorb the shock.
I’ll find out in the next couple of days if I need to do it again.