False Double?

[Refhoop]

Varsity Game Last night:
A1 jumps for a corner 3 in my PCA and before he lands is fouled by B1, attempt is no good.
At what I consider simultaneously; L whistles A4 holding B4 on the rebound.
We both, blow and hold and come together - cause I know he's not calling my corner 3 from the L... he must have something else.
As we huddle, I say we have a false double.
L (most veteran and is a college women's official) and T (new guy) both agree w/one another and concluded; let's go with the "first foul" that happened (corner 3). We didn't an argument from the coaches, but I know we didn't handle this correctly!
1. Is this a false-double or a simultaneous foul?
2. How do we administer this for NFHS?
3. Who gets the next possession and why?
BTW: with rebounding as a POE, I'm thinking we may see more of this...

Thanks!