Account Merge Impact on Invoice History

Has anyone done any account merging???

We are planning to do an account merge in an effort to consolidate a number of "duplicate" accounts.  One concern we have is on invoices and the ability/inability to be able to re-print an invoice.  The merge changes the account number on the merged account's invoice so if the invoice is re-printed after the merge it will not look the same as prior to the merge.

I have the merge audit records to know what account merged into what account but there does not appear to be any history kept on the actual invoice record.