Hi Willem,
What you are looking for is a 'compare'-program that is able to 'look' into files, read real contents and than compare with all other files. If the file is a true copy of another, one of them can be deleted.
Names are often changed, while the contents remain the same.
I do not know a program that can do this yet, but perhaps Denny can help us ?
btw. temps dropped from 33C to 20C within 1 hour tonight.....thanks to the rain.
Roel