Yes! The switch above the microphone inputs that says L/R and L+R does this.

L/R means you're using a stereo microphone configuration.

The option L+R means both inputs will be recorded on both left and right channels, panned center. So you can use either or both inputs at the same time. This is the setting you will want to use. It is good for recording two mono sources, as in an interview with 2 microphones.