He definitely didn’t pay the first time, he just came up with a fake transaction receipt, if OP had actually copied the transaction ID on the re receipt and contacted his bank with that information they would have told you that the transaction didn’t exist then. This case are very common on centralized exchanges so do not believe any documents sent to you with the fake promise that is bank error not allowing the transaction to reflect on your account. It is easier this days to get a fake transaction receipt of any bank
You're too judgemental in this case. It might be truth that he paid and the problem was from either banks due to network glitch. I'm talking from experience because it has happened to me as well just last month. Although mine was not in P2P exchange but it was a similar case. I sent money from one of my bank account to another different bank and it was successful while I was not credited in the receiving bank. At first, I thought it was network issue and I gave it some hours but unfortunately I still didn't receive it after 10hrs passed. I had to reach out to receiving bank for complain since the transaction was successful from the bank I sent from. I was told to wait for 24hrs and if I still didn't receive it after that, I should let them know.
To cut the long story short, I called back after 24hrs elapsed and I was requested to provide the transaction details which I did. The issue was forwarded to their technical support for checks and I received a response that "Dear Customer, sincere apologies for the delayed inward transfer issue, transaction can not be found, kindly reconfirm the transaction details from your bank." I was like ahhhh so this money has gone just like that? No, I contact the bank I initiated the transaction from and update them on what is happening and they confirmed to me that the transaction was successful from their end and if the receiving bank insisted it wasn't successful, I should request for a statement of account so they can check.
As instructed, I requested for account statement and sent it to the bank I sent the money from for checks. I don't know how they both do about it but I received the money after 14 days from the date of initial transaction. The transaction took place on the 25th of August while I reviewed the money on the 7th of September.
If it has to do with another person and I, I would have also assume the person didn't send it in the first place. Some time the problem is from banks actually. I will have to post about this in my local board as well for discussion.