as the older plates were number based and dealers usually get their quota in batches i'm not surprised you'll see a lot of same make cars with same letters etc on for EG : X***XFH was a batch local to glos (via worcs) and everything 300-800 was SEAT's of some and usually majority sold local
did have a list of em a while back but as so many dvla offices are closed/closing and some now cover a wider area you'll find it more common than ever