Not unheard of; as I'm sure
Jack knows, Cleon Jones was a natural lefty, but played in his youth in a park with a very short RF fence where the ground rule was that a ball hit over the fence was an out (to save baseballs, I guess), and so learned to bat RH instead. Brooks Robinson was naturally left-handed, but his dad had played 2B in semi-pro ball, and taught Brooks to throw righty, so he could play infield, too.
Norman Rockwell did a painting of Brooks signing autographs lefty, one-time:
People wrote Rockwell, "correcting" his "mistake". Nope.