To get rid of the dual boot screen itself is easy, but it’s likely that you have 2 copies of Windows on your computer, and you should either get rid of the one you don’t want, or if you want to keep both, then sort out the one that doesn’t work.
What it sounds to me at the moment is whatever you were trying to achieve by installing a 2nd version, you may have selected the wrong options for achieving it, and ended up with a sort of dual boot which you didn't intend to have.
Could you post back with the following information:
(1) What were you trying to achieve when you installed a “2nd version of winxp”? For example, was something wrong with the first version and you were trying to repair the old XP, or were you trying to install a fresh copy (thinking that the old copy will be got rid of automatically)?
(2) How did you go about it? Did you select a new installation, or did you select reinstalling XP over the existing copy, and did you specify a new folder other than C:\WINDOWS to install the new version (if you can remember any of this)?
(3) What do you want to do now, apart from getting rid of the dual boot option screen? Do you want to completely get rid of the “Windows Default” installation as well (because a lot of XP system files will have been duplicated), or do you want to make it work?
[If the 2nd copy is in a separate partition from C, then it has many uses. But if it’s in C as well, then better get rid of it.]
(3) I assume you can still boot into your old XP Home. If so, copy and paste the contents of a file called C:\boot.ini in your next post. Right click the My Computer icon, select Properties, select the Advanced tab, then choose Startup and Recovery > Settings. Then in the System Startup section, click Edit. The boot.ini file will open in Notepad. Be careful here, don’t change anything yet. Copy and paste all the text to your next post. This file will throw some light on what has happened (and where the Windows Default "windows root" is). Based on this file, you can verify how far the “Windows Default” version has been installed on your computer, and whether any folders need to be deleted if you want to get rid of "Windows Default".
I hope the above doesn’t sound too interrogative. Not intended to be so.