A2billing Asterisk CDRS

I Have A2Billing running on Asterisk. I am using the A2billing for call back. I get 2 CDRS for every call back call. Having 2 seperate legs of the call, I need the call durations to be the same. Even though one leg is shorter in duration. I need to combine both legs into one call. The call must add both leg and show the destination number. I do not want this done on A2 billing incase something might break. If CDRs are FTPed out and then another billing interface is complied. From here I should be able to view my cdrs and export it in .txt or csv.