The issue is with e-cheque payments that take a few days to clear (and can be cancelled at any time within that period). If it does go through after a period, then PayPal sends another notification stating its complete.
I will add an option soon to only show completed payments. Unfortunately, this means that people using this payment type would only get the notifications a few days after they have done the act of donating, until the money has cleared from their bank accounts.
