Ah the Newbie with a problem question!

Yes I know, but here goes and TIA for any helpful replies.
I had a problem with a sale on Ebay where someone purchased 4 bitcoins through different auctions. When they paid for the auctions, they used two different PayPal accounts and now one of those accounts funds are being 'Held'.
When I got the Paypal invoice as paid, I Emailed the stated Email address hoping that if I got a response then that would prove the Paypal address and payment was good. I got a response from the paypal linked email each time.
Ok are you done laughing at me yet? LOL

Anyway. My question is how that happened?
Thanks again.