is no sixth replicant; Bryant's dialogue gets it wrong.
An early version of the script called for a character called "Mary"
(Stacy Nelkin was even cast in the role). The character's scenes
were dropped due to budget constraints, but one reference to the
extra replicant had already been recorded and survived the changes,
creating a small continuity error in the process - and giving birth
to a popular theory: namely, the idea that Deckard might himself
not only be *a* replicant, but actually be part of Batty's group
of escaped replicants! This would make Deckard the sixth replicant!
The strange thing is that Scott had Walsh redo the line for an overdub
but then decided not to use it.
According to the theory, Deckard would have been captured and "reprogrammed"
(false memory implants, like they did for Rachael). The fact Roy
Batty calls him by name even though they've supposedly never met
before might suggest Batty knew him, thereby giving impetus to this
theory, although there are other equally valid ways he would find
this out, such as Roy hacking into the police Esper, overhearing
his name or just simply that Deckard has a well-known reputation
as the ace Blade Runner. "Aren't you the good man?" In
fact there are so many holes in this particular theory that many
Deck-a-Reppers acknowledge it as just a continuity error.
Incidentally, the fifth replicant, (the one that got fried), was