My friend and I went out to go hunt for rendermen and we encountered them over 30 times in a single map which was Plate 3.
The Renderman is originally the Zombie face with red eyes then they turn white quickly and then disappears quickly and I actually encountered one in-game. But Mr.shoe (my friend I said) found them most. And I (lolcatz co.) found out that he can be encountered mostly on Plate 3. Destruct didnt work much but you can encounter Doubles. I encountered 2 endermen. One teleported in the sky and then teleported 3 bricks away from that place and it was very odd. I may try to show you some pics when I get a chance to look at them and see if there is any rendermen. Well I hope this proves that the renderman is real and can be encountered in-game. Not just photos.