Can I get one of you VBA guys/gals to help with this one!

I've come up with a way I understand, but can't get the last piece (so I suppose I don't really understand).

I can delete all the dups, but when it comes to the last dup, the concatenated results in column M are 101 which are not unique themselves.

I'm sure I've done this the hard way, so if somebody can help with an easier method I would be very pleased.

As I understand the OPs requirement, the "brown" shaded rows should be deleted.