New GP Implement need to again post into GL ( Account Receivables & Payables )

Hi All,
Actually i am implementing a new Dynamics GP now i have some confusion is that
1.) I have data of GL open including (General Ledger, Account Receivables & Account Payables ).
So i just want to know that is need to import our last closed year data and after import it necessary to post in our new system through GL.
2.) If i post then it reflect duplicates because of we have already GL data of AR & AP & GJ so please guide me how can i solve this problem.

3.) One more thing what about unapplied amount & paid amount , should be there or any other thing?

Please guide me for implement.

Regards,

M.Chi