I'll guess before M2 shows up with a good answer.
I'd say its so that the positions can share the collective control located in the center console. The pilot would of course then choose to fly from the right so that they, being dominantly right handed, could control the control requiring more dexterity with their right hand.
I look around me and I see what I wanted and what I settled for
Yeah, Iíve got the heart of a joan of arc but the soul of a gigolo