Merge History from 2 USBSs

So when I keep a duplicate copy of all my USBs - recently i played a gig where the CDJs were not linked. i ended up having to play with both USBs. when i plug the USBs back into my laptop - Rekordbox imports the play list history from each usb creating HISTORY *DATE* and HISTORY *DATE*(1). 

Is there anyway to merge these without dragging each track into a playlist one at a time? is there any play time meta data? Looking to get an accurate look at what i actually played. 

Thanks, 

Amir