Isolate duplicates across multiple files and process

[WaveOfMutilation2]

Hi All,

Every month I get a dozen or so csv files - normally I would just chuck them all in to one sheet and do this manually but the volumes have increased dramatically (it now totals circa 500k records) so I need some help to automatically extract all the lines from all the files where the contents of the first two columns is repeated somewhere else. For each set of duplicates I then need to check the contents of columns G, F & D against a priority list of values to isolate a preferred record.

I've attached a couple of much minimised anonymised data samples, if anyone can assist it would be much appreciated.

Cheers

Matt