two individuals or groups that are practically indistinguishable
with reference to the two identical quarrelling characters in Lewis Carroll's Through the Looking Glass (1872). The names, however, were in common use for almost 150 years before Carroll adopted them. They originated in a satirical poem by John Byrom (1692–1763) on the rivalry between the musicians G F Handel and G B Bononcini: ‘Strange! That such high dispute should be twixt Tweedledum and Tweedledee’. Here, Tweedledum and Tweedledee are imitations of piffling musical notes, used to suggest that the two composers are negligibly different and indifferently negligible