That's the opposite of what I heard. "Duct tape" came first, "duck tape" is a phonetic bastardization caused by the English speakers finding it difficult to pronounce two sharp consonants in a row.

Talking of which, any idea why some words made by gluing together two words where the second word starts with the same letter as the first word ends with, end up with double letters, but others don't?

Examples:
mis- + place -> misplace (no double letters, but a benchmark to demonstrate no letters are lost)
mis- + shape -> misshape (double letter)
thresh + hold -> threshold (no double letter, one h is dropped)