no idea why they wear out, mine havent yet and its about 6 months old
yes the dual cable needs bobble ends not barrell ends, the one in the link has bobble ends
odyessy also do cables with a barrell on one end and a bobble on the other so if ur using it as a straight cable u cut off the bobble but if u wanna use it as part of a lower dual cable then u cut off the barrell