stupid question about money orders

I am sending a money order… and I have a very stupid question:

There are 2 copies (A carbon copy behind it) Do I send the money order in its entirety or do I keep the back copy?

I know, it’s stupid but the man I’m writing the money order could keep one for records, and the bank could keep one or I could keep one and the other one gets turned into the bank… sorry to make it complicated… it’s not, just stupid.

Thanks for not tearing me apart with an ignorant question.

This is a FWIW answer. I haven’t sent a money order for a couple of years, and I’m in Canada. That said, there was always a copy that I could retain so that if I (or any purchaser) needed to make subsequent inquiries, they could be made. (The money orders I purchased from Canada Post included a serial number on them that could be referenced. )