u guys do realize that most of the time paypal does not have the money before it hits ur account right? the only time they do is if u use an echeck which is why they barely charge any fees on an echeck payment cuz there's no risk to them.
on credit card and bank transfers, they actually pay the recipient out of their own pocket before getting the money. if u've ever paid anyone with a bank transfer on paypal u'll notice that the guy u're sending it to gets it right away but it won't show up as a debit on ur statement for a few days. and that's not just the statement taking time to update, if u check the dates, the money literally does not leave ur account until a few days later. this is why paypal charges fees.
in ur situation if it's from a bank account then paypal will debit the account in question and take the money out before they refund u. if it's from a credit card, they will place a hold on the funds on the card and once that money is released to them, they will refund the money to u. this is to prevent them from giving u the refund and not being able to get the money for whatever reason (bank account overdrawn etc.). they dont want to release the money to u, not get it from the other guy's account then realize that u already spent it. now they're out that amount of money for no reason.
if it's from the guy's existing paypal balance, they're probably waiting for ur initial payment to clear completely before issuing the refund.