Duplicate completion for external commands on Cygwin

[Thorsten Kampe <thorsten@xxxxxxxxxxxxxxxx>]

Hi,

I'm running zsh 4.3.9 on Cygwin and external commands show up twice when 
I attempt completion (see below). The background is that all external 
commands are actually Windows executables (cat.exe for example) and made 
available as commands without the .exe extension by the Cygwin emulation 
layer.

Is there a way to only show "cat" for instance and not "cat" and 
"cat.exe"?

thorsten@tkampe% ca
external command
cabinet.dll  cabview.dll    cacls         cacls.exe  cadaver       
cadaver.exe
cal          cal.exe        calc          calc.exe   calwin32.dll  
capisp.dll
captoinfo    captoinfo.exe  cat           cat.exe    catroot       
catroot2
catsrv.dll   catsrvps.dll   catsrvut.dll

alias
cal

reserved word
case


Thorsten