Double foul?
 

Player A1 takes a layup / goes airborne.
Player B1 has a legal guarding position.
Player B2 does not / steps in the path of A1.
A1, while remaining airborne, hits B1 and then B2.
What's the call?

Charge on A1?
Double foul - Charge on A1 and block on B2?

Does the call differ if the order of contact were changed -
A1 hits both simultaneously?
A1 hits B2 first?

If it's obvious that A1 hit B1 first, then you go with the PC. A1's airborne direction is no a longer a concern with respect to drawing a shooting foul from a B player.

If A1 hit B2 first, then I'd go with the block and not enforce a PC at all.

Simultaneously? I'd have to see such a play. It's similar to the double foul - call the first contact and the double likely doesn't happen. But if you insist it's simultaneous, pick the one that has greater contact.

Rule 6-7 will explain the first part of your Q. Second Q, Juggs has what I think is correct way to handle.