I'm wondering if the backup system could have a delayed queue; say, 30 seconds behind. If the primary fails, and exactly 30 seconds later the secondary system f

I'm wondering if the backup system could have a delayed queue; say, 30 seconds behind. If the primary fails, and exactly 30 seconds later the secondary system fails, you have reasonable assurance that it was queue input that caused the failure. Rollback to the last successful queue input, skip and flag the suspect input, and see if the next input is successful.