Hmmm— we have the Bible account, the Gilgamesh account, —I would wild guess that probably every city in the Elam to Susa to Mari district built a ship to evacuate from the city to escape the flood. Everyone saw Noah building a huge vessel that couldn`t be hidden in a back yard. So I would venture that the jig was up and everyone copied Noah, just as every 1950`s small town in US had at least one crazy guy building a bomb shelter because of the Russian nuclear threat by Bear bombers. I built one too, in 1957, only one in town-ha!
A more likely explanation of the multiple accounts is that they are all based on a single shared memory transmitted into the various family lines originating with Noah and his gang of eight. Please recall that in the Biblical account all of Noah’s neighbors had him sized for a tin foil hat. No copycat syndrome there.