I agree with above, ProSeries doesnt have the ability to Efile a return from some other folder....if the wrong file got sent, and you Efiled from the client file, you had it the wrong file open on the screen, sorry.

I know when I have multiple versions of a client return in motion, Im sure to uncheck the EF boxes on the return that I have no plan to Efile, so it can never be transmitted by accident.    

Highlight the second file you transmitted (thats sitting in limbo) and choose "UPDATE ACKS for Selected Returns" (instead of the regular Receive Acknowledgments), than should get you the rejected message if in fact a return with that SSN was already filed and accepted.  Now go in and uncheck the EFboxes on it, save and exit the file,  to get it out of the EFCenter.

Open the return that was accepted, activate the 1040X and any state amended form (if applicable), then make changes to that return to make it correct, then Efile the amended return, its possible the state amended may have to be paper filed.