I just think that the original production is with Miller as the Creature because in the Making of they showed us at the National Theatre Archive was show that version - with Johnny as the Creature. Otherwise it would have been Benedict.

No the casting dubbed as “Original Casting” is Benedict as the Creature as that is the version NT live screened first - the live version. Reverse casting is Jonny as the Creature as that version was aired subsequently in the UK.

If you go to the NT Archives you can request either or indeed both versions for viewing.