Yes. Actually, we have currently three. DOS/6 has long file names, but OFS block layout. DOS/7 has long file names and FFS block layout. DOS/6 and DOS/7 are exactly as in AmgiaOs 4, but unfortunately not backwards comaptible to DOS/0 and DOS/1. Olaf is currently working on a new DiskDoctor to address this issue.
Then we have another stranger, and this is DOS/8 which will probably go. The fun part about it is that DOS/8 was "sort of present" already in the Os 3.9 version, but there not fully functional. It has 54 character long file names (so more than the usual 30), but is backwards compatible in the sense that the block layout is just like the one in DOS/1, except that unused fields are populated with the extra characters, so old tools will at worst damage the file name, but nothing else.
If you're adventurous, you can test out Toni's patched FFS 45.13 which fixes some bugs and enables DOS\8 long filenames! See
this post on EAB.