Find duplicates with multiple conditions

Dear Experts

I really hope anyone can help me (with preferably a formula in excel 2007 instead of a VBA)on this one cause i'm cracking up my brain:


I want to detect the following and mark it with duplicate:



2940 CAR 105006 78.1 24/02/2010 BA006 15000 80.6
2940 CAR 105008 691.8 24/02/2010 BA006 15000 80.6
2940 CAR 105009 700 24/02/2010 BA006 15000 80.6
2940 600 24/02/2010 BA006 15000





3050 CAR 105006 78.1 24/02/2010 BN005 15000 80.6
3050 CAR 105008 691.8 24/02/2010 BN005 15000 80.6
3050 CAR 105009 700 24/02/2010 BN005 15000 80.6
3050 600 24/02/2010 BN005 15000



i want to locate these duplicates only if in A(line number 2940 AND 3050) and F(reference number BA006 AND BA005) the values are different. I've tried many ways with if countif, but the proble is that i have empty cells (eg under car) in between and the difficulty is that in C (105006, 105008, 105009) & D(78.1, 691.8,700,600) it's the combination of these number that should be found elsewhere in the table

hope someone can help asap..
thanks very much in advance
regards
jane