There was an attempt to fix this in 4d85cde9, and it does avoid clashes between class objects, but it's introduced a new kind of .WHICH clash:
> Int.WHICH
Int|29060856
> for Int, 29060856 { say (.WHICH, .DEFINITE) }
(Int|29060856 False)
(Int|29060856 True)
> Int === 29060856
True
-zefram
