Problem with completion matching control

[opk@xxxxxxxxxxxxxxx (Oliver Kiddle)]

I've noticed the following behaviour which makes some sense but seems
like a bug when first noticed.

zsh -f
:> Temp
:> temp
compctl -M 'm:{a-z}={A-Z}'
less t<tab>

Results in
less temp
      ^ - Cursor here. 'Temp' and 'temp' are listed below

So it if filling in the 'emp' which is unambiguous but moving the cursor
back which I find very annoying. In my opinion, it should either
complete to 'temp' or just beep and list the two files. The former would
probably be better. Can the semantics of matching control be changed to
accomodate this with out breaking it's other uses? i.e. Are there cases
where the cursor moving back is useful?

Thanks

Oliver Kiddle