> > folder: area51r3k -- contains: area51a.chd
> > folder: area51 -- contains: area51.chd
> > folder: area51a -- contains: area51a.chd
> > folder: area51mx -- contains: area51mx.chd
> > I do NOT have a folder for area51mxr3k or an area51mxr3k.chd
>
> That's theoretically all ok for split-merged sets. Do yourself a favour and save
> 500 MB by deleting one area51a.chd and keep the other in the area51 (not
> area51a) folder.
>

So I would then have this?...

folder: area51 -- contains: area51.chd & area51a.chd
folder: area51mx -- contains: area51mx.chd

DELETE folder: area51r3k
DELETE folder: area51a