Scheduled transactions are paid only after the sync process finishes (so MoneyWiz knows if the transaction was paid on another device already). Can you check if your devices are always syncing a lot of data when you launch them? If you do not sync your devices frequently, they'll have more data to sync on each launch.
Can you try restarting MoneyWiz when this happens and see if this helps?
Have you tried restarting MoneyWiz?