Noun
(derogatory) Two persons or organizations deemed indistinguishable in some way.
The radicals said that Nixon and Humphrey were Tweedledum and Tweedledee.
(derogatory) A pair of people who spend a lot of time together, and look and act similarly.
Source: en.wiktionary.orgOur democracy is but a name. We vote? What does that mean? It means that we choose between two bodies of real, though not avowed, autocrats. We choose between Tweedledum and Tweedledee.... Helen Keller
Some say, that Signor Bononcini, Compared to Handel's a mere ninny; Others aver, to him, that Handel Is scarcely fit to hold a candle. Strange! that such high dispute should be 'Twixt Tweedledum and Tweedledee. John Byrom