Source : Webster's Revised Unabridged Dictionary (1913)

Tweedledum and Tweedledee \Twee"dle*dum` and Twee"dle*dee`\
   Two things practically alike; -- a phrase coined by John
   Byrom (1692-1793) in his satire ``On the Feuds between Handel
   and Bononcini.''

Source : WordNet®

Tweedledum and Tweedledee
     n : any two people who are hard to tell apart [syn: {Tweedledee
         and Tweedledum}]