inconsistant contents of a directory

[Duncan Lithgow]

I'm getting different results for the contents of a directory. On the
command line I get:

duncan at ubuntu:/media/storage/duncan-win/arkiv/tax-skat$ ls
skat i dk-2004  skat i nz-2004  skat i uk-2004

But in nautilus I see two copies of each directory. I can navigate each
one and they're still there if I come back up from each one.

I can see that if I rename one of a pair they other 'copy' simply
disappears. Could this be something odd because of different ways of
recording the empty spaces in the file name? When I changed the name I
replaced those spaces with underscores (_).

I've left one of them untouched so we can try to come to the bottom of
this.

Duncan