Why are there 3 2.9.2 ISO files?

There's this one:
linuxcnc.org/iso/LinuxCNC_2.9.2-amd64.hybrid.iso

And this one:
linuxcnc.org/iso/linuxcnc_2.9.2-amd.hybrid.iso

And this one too:
linuxcnc.org/iso/linuxcnc_2.9.2-amd.hybrid.iso

On my mirror, www3.langdonstaab.ca/iso, I would like to remove these likely duplicates to reduce bandwidth and load for my server in the event that someone downloads all the files on my server (with wget -r or something).

Are these files identical?

Why are they still there?

Which one is actually correct?

langdons wrote:

There's this one:
linuxcnc.org/iso/LinuxCNC_2.9.2-amd64.hybrid.iso

And this one:
linuxcnc.org/iso/linuxcnc_2.9.2-amd.hybrid.iso

And this one too:
linuxcnc.org/iso/linuxcnc_2.9.2-amd.hybrid.iso

On my mirror, www3.langdonstaab.ca/iso, I would like to remove these likely duplicates to reduce bandwidth and load for my server in the event that someone downloads all the files on my server (with wget -r or something).

Are these files identical?

Why are they still there?

Which one is actually correct?

They should be identical builds, but sometimes the project keeps multiple copies for mirror syncing or testing purposes. You can check the file hashes (MD5 or SHA256) to confirm before removing any duplicates from your mirror. 

I deleted all other files.

(And fixed the directory structure!)

Now it's just wheezy and 2.9.4.

2.9.4 and Wheezy now accessible via:
www3.langdonstaab.ca/LinuxCNC/
www3.langdonstaab.ca/LinuxCNC/iso/
and
www3.langdonstaab.ca/iso/

Random Ubuntu Server question:
Why does the du command show the symbolic link (created via ln) as occupying space and not the actual file?
Really strange.