It's hard to say... we really have no clues to suggest when the tile-flipping functionality was added to JJ2. It was in 1.00g and even diamsecr, so it's got to be pretty old, but it's impossible to say if it postdates the Jungle tileset. Simple answer, though, one way or another, Nick wanted to add more potential variety to leaf appearances and didn't consider the fact that it would mess up the tiling.