We can figure out what's causing the increase, topshelf.
As long as the bank accounts are reconciled, you are good. There's nothing for you to worry about.
Let's run some reports to verify which accounts your customer mentioned that get doubled. You can start with these:
Compare each report to verify if there's a discrepancy. If there is, please check out this article to fix it: Fix Reconciliation Discrepancies.
Please get back to us if you've got another question. We are right here to help you.