Checking for Duplicate entries

[rgmelin]

How can i check for duplicate entries. My logbook times in logbook pro 1.9.6.5 don't match the times in airlinelogbook PDA version.
If i do a summary jan 1 2005 - aug 31, 2005 logbook pro shows 656.9 hrs

Airlinelogbook ver 3.05 summary for jan 1 2005 - aug 31,2005 shows 456hrs 50mins

Thanks
rgmelin