Con, Paul Sammon stated that were was an  alternate take on the scene where Batty kills Tyrell. In both (the theatrical  and directors) cuts, we see Isidore flee in horror after Batty puts both of  Tyrells eyes out. But allegedly in the shooting script there was a line  where right after Batty killed Tyrell, Isidore stepped up to him and said  "No, no, that was too easy. WHERES THE *REAL* TYRELL?", meaning that the  Tyrell that Batty killed could have been a replicant, and that Sebastian  could be a replicant too since he guessed that Tyrell could be one.