Ok. Thinking about the original problem, you have a number of 'historical sales' that shouldn't have been there because they were either double-ups or should have been written off. If this is the case, then instead of reversing the historial sales, you should actually post a new document such as a credit note against that debtor. The credit entries will post into the debtors ledger to get rid of the balance and the debits should be charged to a new account in your P&L like 'pre-conversion write-offs'. This is the correct accounting treatment given the previous profits were over-stated. You shouldn't then have to do any adjusting journal entries given you have created new documents within the debtors ledger.
If you try to reverse the historical sale, what you are effectivley saying is that the opening balance of the debtors ledger account and the opening balance of the retained profits account are both incorrect (plus any sales and income tax effects). However, assuming the prior year accounts were finalised such that your starting point was the Balance Sheet at 31/12, then reversing the items in this year is the correct thing to do.
HTH, Andrew