Comma in path

Hi all,

Great software, great forum, quick question.

Ubuntu Edgy,  GParted 0.2.5, parted 1.7.1. I have a partition and mountpoint  that looks like this in GParted =>

/dev/hda4      /,/dev/.static/dev

I reinstalled Edgy due to a video card disaster which involved using an older standby. I threw the new one on hda5 so I could go back to the old one on hda4 without having to mess with the X server/device drivers/et al.  hda4 is a primary and hda5 is an extended partition under hda3. I can boot into hda4 out of GRUB with some bizarre mountpoint like (on hda5)(on hda4) or mount hda4 after booting into hda5.

Here's where it gets strange. If I mount hda4, any changes I make to my home directory on hda5 are immediately reflected in the hda4 mountpoint home directory and vice versa.  Also, the Unused sizes are identical =>

hda4 - 9.15G/5.12Used/4.04Unused
hda5 - 8.85G/4.81Used/4.04Unused

This is not a coincidence as I copied a 1.2G file into the hda5 home directory and they both dropped to 2.84G.

I'm just really curious about what I've done here and would like to know the answer before I blow the whole mess away.

Any input or feedback much appreciated.