in whatever recording software you are using you should be able to select what inputs you want to record with per track.... it would help a little if i knew what program you are using.
i am guessing you are using the 1st input on your recording interface? if so you need to set up the track you are recording on to as mono record only.
i dont know how many inputs you have but most likely they are laid out like this input 1 and 2 are a stereo pair, 1 being left channel and 2 being right channel.. every proceeding group of inputs are the same
that being said you should understand why you are getting a signal only on the left channel.....
you dont have to use 2 mics. just set up the track to be recorded on as mono. again if i knew what prgram you are recording into i could help more.
i saw your post on recording.org and i am surprized they didnt explain this to you.