Duplicate WordWheel registry key

Microsoft Office Word Docmanagement

I discovered a duplicate program class key in HKCR for 
Microsoft.ITIR.WordWheelBuild.5.4. The first key has a default value of 
"Microsoft Infotech ITIR Word Wheel Build" and the second is 
"Microsoft.ITIR.WordWheelBuild.5.4". They both have the same CLSID of 
{3E6C7FFD-743D-4265-8E3D-0D7EA889DFDB} which is itircl54.dll. Other systems I 
have checked have only the first key. The questions I have are:

1. Shouldn't program class keys must be unique?

2. What is the possible affect of deleting second (assumed to be duplicate) 

3. What is WordWheelBuild 5.4?
No. The CLSID identifies the file or library to use (itircl54.dll in this 
case). The key identifies the CLSID, and there may be more than one. This 
technique is used to deal with different versions of an app. Eg, if you look 
up "Word.Application" you'll get the latest version you have on your 
computer, which might happen to be "Word.Application.11"; but you might also 
have "Word.Application.9" still available for some legacy application that 
needs that specific version.

An application looking for that key will fail.

Part of Microsoft Infotech.
I think what you are saying is there can be multiple keys for the same 
application such as Word, each pointing to a particular vesion. This makes 
sense assuming the key "Word.Application" would point to the default version 
(say 11) while the keys for "Word.Application.9" and "Word.Application.11" 
would point to their respective versions.

However, in the case I have uncovered, the two keys are identical except for 
their default value and they point to the same dll. To use your example - 
what happens when there are two keys, both with the same name - 
"Word.Application"? Which one is used?