The State of California does not allow license plates to have the same sequence of letters and names, irrespective of spaces. I believe the same should be true of FT handles.
Glen, your suggestion is a reasonable one - but it requires that ozstamps be aware as soon as an oz stamps comes on the board (for example). And if that person posts in forums you don't read, they could be onboard long enough that they aren't eager to change.
In my example of 4 miles and 4miles, each has just a few posts. I believe that 4miles came later than 4 miles; yet his inaugural post was so charming and clever that he instantly created an identity he should be loathe to give up.
Rather than us having to check the boards individually, I believe it should be an easy software change for FT to implement.