Mystery transactions appearing when I do the next month's bank reconciliation

Hi

I reconcile my bank accounts each month after importing the bank file, allocating transactions to the appropriate income or expense code and then reconciling the account.

Twice now when I go to reconcile the next month - after the same process - I have many transactions (14 in fact) sitting there as unreconciled from the previous month. This freaked me out the first time. After investigation I realised they were not showing up in the accounts the unreconciled transaction were supposedly coded to. So when I delete them the account balances for the income and expense accounts are not affected. Where would these transactions be coming from. They are not generated by bank rules or templates.