I goofed once and included a check to the garbage company in the payment to JC Pennys. Both checks cleared the bank and the money went to JC Pennys.
I used to work at a place that did that all the time. I believe the process for payments was entirely automated. People would accidently send us their rent checks and we would cash them. That was always fun to tell people…
as i said of the hundreds of checks I have deposited I never had any returned because my lack of signature