It's a scam.
No one on earth would give you a deposit from another person's 3rd party account.
Do not refund the money.
You broke Paypal's rules by using Friends and Family to accept money from a stranger
You broke common sense rule, never get into a payment transaction involving a 3rd party
You broke Pinball's #1 rule: NEVER ACCEPT PAYPAL FOR PAYMENT ON A PINBALL MACHINE
Quoted from radiomoz:I just want to confirm that the transaction is legitimate.
How exactly are you confirming this?
Quoted from radiomoz:I’m an honest guy and have a highly respected pinsider that can back me up if need be.
Who is this "highly respected Pinsider" exactly?
Who's 3rd party Paypal account did you use, and why did you not just use your own?