Proposed resolution:
This wording is relative to N4885.
Modify [counted.iterator] as indicated:
-3- Two values i1 and i2 of types counted_iterator<I1> and counted_iterator<I2> refer to elements of the same sequence if and only if there exists some integer n such that next(i1.base(), i1.count() + n) and next(i2.base(), i2.count() + n) refer to the same (possibly past-the-end) element.