Someone “accidentally” sent me $100 through Zelle. What should I do?

I’m 100% aware of the scam attempt where they send money with fraudulent funds/accounts, beg you to send it back, then the bank pulls the initial payment from your account after a week or two. In this case, the answer is to do nothing.

However, despite this concern, not only did the sender call me, but the number that the money was supposed to go to also called me. I didn’t answer the calls because I didn’t recognize the numbers, so they also texted me and both are “iPhone numbers.” Also, the number who the money was supposed to go is 1 number off of my actual phone number. So the “typo” story is a bit believable. Further that, when the sender was explaining the situation thru text, they noted that the registered name on Zelle (my name) is technically a shortened version of the actual name of the intended recipient. As a precaution I told them I hadn’t received the money (which is a lie it’s in my account) and to file a claim with their bank but they said they tried and their bank can’t do anything. And in response to me not seeing the transaction in my account, they sent a screenshot from their banking app of the Zelle payment, and while they tried to cross out their balance, it doesn’t look like they have insufficient funds

So with that said, should I send the money back? Should I wait and then send it back and if so how long should I wait?