Can I disable some autoformatting for posts? (i.e., double hyphen to em dash)

[hemes (Brett Hemes)]

The ones from eXtreme Gammon program do but we also have users posting GNU Backgammon IDs. They do not have a prefix. E.g.:

jM/gDQDYzeAJIA:EQFvAAAAAAAA

… but these also don’t use hyphens so don’t suffer from the same markdown auto-corrections