How do I resolve an accidental double spend? I made a double payment to the same address mistakenly since my internet was a bit slow, and one payment has 8 confirmations. The recipient says he hasn't received it. I got this message from the transaction: 


  A conflicting transaction has been detected in our memory pool. The transaction hash displayed below may change.


What can I do to resolve this?
A double spend is not possible. A double spend attempt, yes. You might try and (accidentally or intentionally) broadcast two different transactions that spend the same bitcoins. But only one will eventually get included in a block.

If you say one payment has 8 confirmations, then that's the one that became final ('set in stone') and the other will never happen.