Doppelganger

I'm thinking about how, in a stage play, you sometimes can get one actor playing two parts. Sure, sometimes it's because you're short on actors, but sometimes the play is trying to tell you something via the choice of actors with regards to characters, about how two people are metaphorically the same. I even saw someone talk about a play where the main male romantic lead actor and the villain's actor would swap, night to night, so if you saw it more than once, you'd see the protagonist struggle with her choice between two different men, despite making the "same" choice every night by doing what the script dictated.

Maybe this is something unique to the medium of stage plays, but I can't help wondering how you'd accomplish the same technique in a standard text medium, or in something like a TTRPG. Certainly if, for example, I saw a character in a Pratchett book start talking in smallcaps, I'd think something was up with Death, but fonts can be distracting if not used well. TTRPGs have the additional problem that as the DM, I'm already every character. How do I key that same level of similarity, of familiarity, that a character being played by the same actor would have? Hm.