If you have a single partition, and if there are two versions of XP installed, then one will be as windows and the other will be something slightly different... What each is labelled will be clear via the boot.ini. This because the boot.ini entry for each will be slightly different in terms of the XP folder name.
If each version is in its own partition then both will be in as windows... (as you are using XP-Home); but the partition number will be different.
So boot to the one you want to keep; set it as default OS to boot; then via XP/Windows Explorer check to see if you do have two differently named XP folders on the drive/partition. If you do and you're sure which one you're using and want to keep, then simply delete the other one. Reboot to verify all is still OK with the one you want to keep; presuming so, empty recycle-bin and defrag the drive... Then go back to the XP location (MyComputer etc..) where you set default OS to boot, and delete the redundant entry from the boot.ini - the entry for the deleted version. Job done.
Set default OS/edit boot.ini via:
MyComputer\Properties|advance-tab/startup etc button/option...
Any doubts as to what to delete etc... post the boot.ini as is here first (ideally after you have set default OS to boot to be as you wish).