Recording stereo guitar signal onto one track

[RickH]

I have an iPad 3, iOS7. Up til now I've been using Garageband but I've not been able to figure out any way to record a stereo signal onto one track, coming from a Digitech RP50 effects box, or from a Behringer mixer using two microphones panned hard left and right. In spite of using Sonoma's Guitarjack 2, the playback signal on the recording is always in mono. So, can I use a single track in Multitrack Daw for recording a stereo signal, or would I need to simultaneously use 2 tracks?