Hm, i found all of them in the list.
The line numbers of the 15 above are
141, 2247, 3514, 5232, 5913, 12884, 14683, 15658, 17087, 18102, 18766, 24382, 26355, 26753, 28348
[Added:]
If you have gsf's program and unix tools you can find new ones this way:
Canonicalize the list:
sudoku -qFN -f'%#0c' sudoku17.txt > sudoku17.can
Canonicalize the puzzles:
sudoku -qFN -f'%#0c' puzzles.txt > puzzles.can
[Edit:]
Eliminate equivalents:
sort puzzles.can | uniq > uniqs.can
Find duplicates:
grep -f uniqs.can sudoku17.can > dups.txt
Get those from uniqs not in dups.txt:
grep -v -f dups.txt uniqs.can
I am sure, gsf knows it better ...