I think the second GF would only come out if they try to jump or backdash, etc. Otherwise I don't think anything would happen just like if you were just standing around and did 22D (no GF, just a D move).
But I don't think it would give you a D move either if you did it during the first GF since it would be in the middle of Gadget Finger. Gotta try it and see.
Basically, if they jump or backdash, they get Gadget Finger'd again, if they don't then 5A comes out. And you could just keep doing it forever if it works.