If you have a mental picture of Tweedledee and Tweedledum as round-bellied identical twins, you're heading in the right direction—through the looking-glass—but don't linger too long in Wonderland. Although Lewis Carroll popularized the Tweedle boys, he did not invent them.

Tweedle, meaning "to chirp," is believed to have been born as an imitative term in the late 17th century. Credit for adding dee and dum—imitative of high and low musical notes, respectively—to tweedle belongs to 18th-century poet John Byrom. Byrom created the figures for a satire entitled, "On the Feuds Between Handel and Bononcini." Although Bononcini is no longer considered a serious rival to Handel, during their lifetimes the two men were quite competitive, inspiring Byrom to observe:

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.