proceed payment twice, what should I do?

[Zhang Weiwu]

This sounds silly but I think i processed payment for the same invoice
twice, once early this month and the second time now. And I have saved
my file.

What should I do? Can I simply delete the transaction of the second
duplicated payment on the account "Saving account" which is where money
is paid to from "Account Receivable"?

I am also a bit surprised that gnucash allowed me to do it. I thought an
invoice would have been marked as paid once I proceed payment, and not
allowing me to do it again.

Thanks in advance!