IN WHAT HE CALLS "This follow-up of mine to Ko . . .," Kenneth Koch has created another comic-book epic filled with "characters beaked, snouted, nosed and billed" who undergo numerous impossible experiences. The Duplications is something of a nonsense epic whose seriousness lies more in the demonstration of Koch's impressive technical skill than in the narrative itself.

"Has it ever occurred to you," the poet Ampleforth asks Winston Smith in 1984, "that the whole history of English poetry has been determined by the fact that the English language lacks rhymes?" Through more than 450 rhyming stanzas, Koch refutes Ampleforth's notion. Although there are many "duplications" in the story --brand-new versions of old cities, "Early Girls" created out of dirt, etc. --the duplications that are really at the heart of this poem are the rhymes.

The Duplications is a tribute both to the possibilities of contemporary English and to the vitality of traditional verse forms -- in this case the ottava rima, used by Byron for Don Juan. Ottava rima, whether in Italian or English, is a verse form that has traditionally lent itself to work of an unorthodox blend -- funny, serious, ridiculous. Like Don Juan, The Duplications is allegedly a narrative, but the story is not important. What matters most is the way the poet's mind works and the language he chooses to reveal himself and his attitudes. Some critics, no doubt, think that. An epic should be moral and found, a saga of the mighty and sublime. It stirs the soul with heroes who astound us with deeds that stand the test of time. But most of them are boring, I have found, and I wouldn't buy a dozen for a dime. This poem, though, is more an epic joke --The Duplications (read it!), by Kenneth Koch.