"Duck tape" is recorded in the Oxford English Dictionary as having been in use since 1899[2] and "duct tape" (described as "perhaps an alteration of earlier duck tape") since 1965.[3]
It was originally used for making shoes stronger and was later used for sealing ammo tins.
Suposably, errors like this happen because people are playing it by year. For all intensive purposes complaining about it is a mute point though - unless they are doing it over and over and for a pacific reason, e.g. because of oldtimers desase.