Mono vs. stereo export output

I'm creating scores and then exporting them as .WAV files to be loaded into a Tascam DP-006 Portastudio for fun (mostly overdubbing and some rudimentary mixing). The Tascam only works with .WAV files. I have noticed that .WAV files exported from Muse Score come out as stereo, requiring me to either send it to one of the stereo channels on the device or to tie up two mono channels. Is there an option to export tracks as mono (I have a sound file converter so the output wouldn't necessarily have to be .WAV)? Thanks!