How do I can cancel a double payment

[Dommart]

How do I cancel a payment which was made by mistake to a friend, not a vendor. He said it is withheld for 72 hours. I told him to send me a request and he did, but PayPal told him he has to wait 72 hours before it goes in his account. So he made another request and that went through. Now I want to cancel the first payment before it goes into his account. How do I cancel it?

[kernowlass]

@Dommart 

You ask him to issue you with a refund for x1 of the payments.