Collection pages could overlap?

In 4.6.1 Collection Paging the CollectionPage class is described:

the items within a Collection can be divided into distinct subsets or "pages"

Also, CollectionPage in the Activity Vocabulary provide a definition of collection pages

Used to represent distinct subsets of items from a Collection.

In both the reported fragments, pages of a collection are defined as distinct sets. In set theory, two sets are distincts if they differ for at least one element. Thus, distinct subsets can overlap. In our context, this implies that two pages of the same collection may share items, provided that they are not exaclty the same set of items.

Is it the intended meaning for Collection Pages? If not, we may just change the world distinct to disjoint in order to avoid collection pages overlapping.