Use Same User-defined Constant In 2 Enum

I found out that using Enum one can have a dropdown box to choose from when inserting a parameter in a function.

But how can I have the same user-defined constant in more then one Enum? It works with standard VBA variables like vbEmpty, so why not with self made constants?

I tried this which gives the error: Ambiguous name detected

Code:
Private Const vbTest = 99 ''' = Ambiguous name detected !!!
Enum eTest1 '''gives 3 choices
vbEmpty ''' = standard VBA 1
vbLong ''' = standard VBA 3
vbTest ''' not in VBA, so I would assign 99 to it
End Enum

[Code] .....