You may see voided payments in Sage Intacct where there's no record of the corresponding payment in Bill.com being voided. This happens when an update is made to the payment in Bill.com (such as to the memo field) after the payment has already synced to Sage Intacct.
When an update like this is made to a payment in Bill.com, the payment is voided and reissued in Sage Intacct. This is because Sage Intacct doesn't allow updates to payments after they've synced. This is normal and expected behavior.