"...With a very few trusted clients, I ask one to sign for both"

MY solution for that is.....  'Isn't s/he in the car down in the parking lot?  Out the front door/back in seconds with the second signature.  <w> <nod>.

MY position on this is, if/when the e-file police show up - that's my signal to just go ahead and retire.  But I'm relatively close to that decision anyway so it wouldn't be a problem.  Well, it might be for my clients.