Yeap. In fact that was the very very first Duel Test map ever used by us (here is an old pic):
You can do this with any map. I would suggest copying the map then renaming the copy (dont want to loose your original). However smaller maps work well as some larger ones it would take all of the duel timer to find the other person/bot We are playing around with getting ChaosCTF to load both CTF and vCTF maps so once we get the bugs out, we may come back and let Duel load 1on1 maps as well....
As a note, small CTF, DOM, and BR maps work well for this, too. Not sure if I have any reccomendations as for maps themselves, but it is nice to find a new arena every so often.