There have been more than a few different versions of Kryten throughout the series Red Dwarf. And here they are. :)
Click on the name to see a picture.

Bongo - Kryten in a different reality, one of Ace Rimmer's companions. (From episode Dimension Jump.)

Jack Bullet - Who Kryten thinks he REALLY is after being affected by hallucinagens from a creature called a Despair Squid. (From episode Back to Reality.)

High Kryten - After an accident with a replicator occurs, two replicas of Red Dwarf (along with all of its contents, human and otherwise) appear. One of them bears all of the good aspects of Red Dwarf, being completely flawless. This is the Kryten encountered on that ship. (From episode Demons and Angels.)

Low Kryten - This is the Kryten found on the other ship, which is the perfect replica's polar opposite. There is no good found anywhere about this replica; everything is very, very bad. (From episode Demons and Angels.)