an impossible task,
The registry has thousands, if not tens of thousands of entries in it, and trying to keep it small and clean and tidy would be a mammoth task, perhaps a lifetime one.
Registry cleaners are very good, but use with caution as they cannot always identify which keys are truly redundant, or just sleeping, waiting to be called upon at some stage in the future.
Added to that, with so may entries, there are bound to be duplications. For instance, there may be many entries under HKEY_Current_User_Software_Microsoft that are repeated under HKEY_Local_Machine_Software_Microsoft, and removing one apparently duplicate entry may render your computer Operating System as a list of 1's and 0's, with no more meaning than that.
The Windows XP registry is a much more robust animal that the previous versions were in Win 95, 98, and ME, and is much better able to handle aberrant entries without constantly falling over. So, although it is good that you take an interest in the registry, and keep an eye on it for obvious orphan entries that can be removed, the need to do so constantly is no longer so pressing as it was in the older WIndows OS's.
In addition to all of that, your question did not give too much away about whichh registry keys you were scrutinising, so it's difficult to give any satisfactory answer to your question.
There's an old addage. If it ain't broke, don't fix it. I feel that way about my own registry.
As to my Windows register i keep a 'clean house' I have various programs that clean it up form me. But inspite of that i still see a lot of entries that are the same. The only difference is the have a .1 or .2 or .3 after the keyname. My goal is to keep the register as small as possible. So here's the Question:
Does anyone know where these entries come from?
What are they for and
Is there is a program that can delete them (keeping the most recent ofcourse)
Any light upon this subject is appreciated
(Nomen est Omen)