Flexo

Flexo is a bending unit fresh out of robot prison, identical to Bender in every way except for the little goatee that marks him as an ex-con. Calm, polite, and oddly reasonable where Bender is chaotic, he gets swept into the crew's schemes purely because nobody can tell the two robots apart.

The joke is structural: John DiMaggio voices both robots identically, so the humor comes entirely from other characters' confusion and Flexo's unbothered reactions to being mistaken for a much louder personality. He's a sly bit of stunt casting turned into character work, letting DiMaggio show restraint as the same voice becomes a different man.