if-else bug or what?

MT 2.9

When I try to execute

:if (1=1) do = { 
   :if (0=0) do = { 
      :put "a" ; 
    } else { 
       :put "b" ; 
     }; 
} else { 
  :put "c" ; 
}

I get this error: argument given more than once (else)

It seems like MT script cannot do nested if-else.

This will be fixed in future releases.