Cut Lawquane: You and I may be clones, but we’re still individuals. You have a name rather than a number, Captain. Why is that?

Captain Rex: Perhaps our leaders feel it’s a more efficient way of distinguishing us.

Cut Lawquane: More efficient than a number? I doubt the Kaminoans think that way.

From Star Wars: The Clone Wars – Season 2 Episode 10: ‘The Deserter’ (2×10)