well I haven't played much World Tour yet, but I've played with two players that has an error in his backhands:
-Mardy Fish has a 2 handed backhand, not 1 handed
-Agustin Calleri has a 1 handed backhand, not 2 handed
if I notice more I'll post them here...
edit:
Arnaud Clément has a 2 handed backhand, not 1 handed
Vincent Spadea has a 2 handed backhand, not 1 handed