Tweedledum and Tweedledee: Meaning and Definition of

Twee•dle•dum and Twee•dle•dee

Pronunciation: (twēd"l-dum' un twēd"l-dē'), [key]
  1. two persons or things nominally different but practically the same; a nearly identical pair.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.