Bank Reconciliation

Hello,

When we go to do a bank reconciliation for two of our bank accounts, several transactions that have already been reconciled show up with the transactions that have yet to be reconciled. When we print off the reconciliation report, these transactions show up as uncleared transactions. Would anyone be able to tell me why this is happening, and if there is a way to fix this without undoing previous reconciliations? And also, it this likely to impact our BAS?

Thank you for your help.