Remove duplicate Windows installation

[Michael]

I have two same Windows XP OS in my computer.
How do I remove one of them?

[Rob Pomeroy]

How do you know that you have two installations on your computer?

[Michael]

Because I installed two.

[GX1_Man]

I wonder why you did that.  

[Rob Pomeroy]

Did you install them both to the same partition?  To the same folder?

[Michael]

Actually it was my sister.
She used to have only one XP OS on her laptop, and when she tried to install Norton Antivirus, the Windows stop responding everytime booted into desktop. All desktop icons and Start Menu are not responding.
So she ran the recovery disc, the recovery somehow installed a fresh XP OS on the laptop. So she got two now.
After I fixed the initial installation, now I want to remove the later installation and use only the initial one.

[Rob Pomeroy]

I repeat: how do you know there are two installations on the hard drive?  This sounds like the original installation was repaired or overwritten.  What makes you think that there are two, distinct installations?

[Michael]

Did you install them both to the same partition?  To the same folder?

Same partition different folders.

[Rob Pomeroy]

What are the names of the folders?  And do you have two separate "Program Files" folders?  If not, you don't have two distinct installations, because Windows shoves some stuff in there and you will have virtually no way of determining which files and folders belong to which installation.  Why not just backup data, reformat, reinstall at this stage?  As GX1_Man often points out, that can be a good opportunity to clear out all kinds of crud, and make your system lean and mean again...

[Michael]

What makes you think that there are two, distinct installations?

I am prompted to choose which to start during start up (OS selection page), and I can start both OS identically.
Is that clear enough?

I don't know how was the folders situation as the laptop is with my sister abroad.

Of course I know a formatting will solve everything - if only she don't want to keep the files or she has a CD writer to backup all her files.

In that case I don't even have to post my case here.

[Rob Pomeroy]

Nope.  See my previous post.

[Rob Pomeroy]

Oops - you edited your post whilst I was replying.

I don't know how was the folders situation as the laptop is with my sister abroad.

Well my crystal ball is away for repairs so I'm stuck too.

Of course I know a formatting will solve everything - if only she don't want to keep the files or she has a CD writer to backup all her files.

Why not just remove one of the options from the boot menu?  Would that be okay?  You could then delete the corresponding Windows folder, although I can't promise that wouldn't cause unpleasant side effects.

[Rupununi]

I have a simular problem, would you please explain to a real dummy how to delete the duplicate instalation   Why not just remove one of the options from the boot menu?  Would that be okay?  You could then delete the corresponding Windows folder, although I can't promise that wouldn't cause unpleasant side effects.

thanks in advance

[Michael]

I am looking for a proper way of clean removal / uninstallation.
Thanks for your alternative solution.
Maybe my initial question was too general.
I think you've brought unnecessary complication to a simple straight forward Q&A.
Sorry if that offends you.

[Rob Pomeroy]

I am looking for a proper way of clean removal / uninstallation.

And I have explained why that may not be possible.  I'm happy to explain again if I haven't put it sufficiently clearly.