[Paul Maunder]

Panning them both hard left and then exporting to multiple mono won't work either as automation data is ignored when exporting. I've worked out how you can do it though! My previous instructions were correct up to the point where you actually export the files. Since there's no summed mono option, export them as a stereo file instead and then take them into itunes. By changing the import preferences in itunes to mono WAV, you can convert your stereo file to a summed mono one by selecting 'convert selection to WAV' from the 'Advanced menu'. I've tried this and it works!