You can use a "single-point stereo" microphone, but most of the inexpensive ones are designed primarily for business recording (office meetings, etc.) and have poor characteristics for music pickup, no matter what the marketing brochures may say. Mostly they emphasize the range of frequencies that make speech easier to understand--but recorded music usually sounds best when you don't mess with the frequencies very much. And nearly all low-cost stereo microphones cover too wide an angle for the distance that most people have to record music from. That makes music recordings muddy sounding (too much room pickup), and the performers all sound as if they're standing in the center of the stage.
In most cases it's easier to control those factors with separate left and right microphones. Professional-quality stereo microphones exist, but they tend to be extremely expensive and they aren't very flexible solutions.
--best regards