multiple alias this in class/struct not allowed?

[Adam Cigánek]

Hello,

Why are multiple alias this declarations in a class/struct not
allowed? This page
http://www.digitalmars.com/d/2.0/class.html#AliasThis says so, and
also dmd2 gives me an error when I try to do it, but TDPL says
something different (on page 231): "a class could introduce any number
of alias this declarations, thus subtyping any number of types."). Did
this feature change? Or is it a bug?

adam.