Get all mutations on a document in DCP

Hi, found info in DCP doc indicating we might get multiple versions for a key. See https://github.com/couchbase/kv_engine/blob/master/docs/dcp/documentation/concepts.md.
In Deduplication section

However, when multiple disk snapshots are merged logically into a single DCP backfill snapshot deduplication is not done.

It seems to contradict the said answer. Am I misunderstanding something here ?
@drigby ?