Alt 8th Doctors query! (Big Finish)

[u/ToshirosMyHero]

I'm currently researching alternate versions of the Doctor - can anyone clarify whether the following versions of the 8th Doctor are temporary changes, parallel-timeline versions of the Doctor, duplicates, or something else?

• The 'Axon Doctor' from 'Master!': "Planet Doom"): McGann in his new series costume, with gold skin and pin-pong-ball eyes
• A partially Krynoidised 8th Doctor in 'Planet Krynoid': "Nightfall").

Thank you!