I once had two scammers at the same time send me fake money orders. I
played along with each of them, pretended I cashed the checks, packed
up the item, etc, never mentioning the other scammer.

Then just as they were sure it was a home run, I started intentionally
mixing up their email addresses and names... slipping the other
scammer's email address or name into the replies.

As time went on I intentionally replied to each of their emails, but
to the other scammer's email address. I was sure to include the email
address for both scammers in the email as if I thought it was the same
person... except I made sure that where I told one person I was
sending the money was NOT him but the other guy.

They BOTH thought that I had fell for the scam completely, except they
each thought I had accidentally sent the money to a rival scammer...
at this point they each started fighting with each other over who had
the money and I got dropped from the conversation.

This was really entertaining to watch!