Anon, I mean this in the gentlest, most understanding way possible.

When you say “DID just as a coping mechanism”–

From a psychological perspective, what do you think DID is?

It’s absolutely normal for switching to activate in response to coping with a stressful situation.

It’s absolutely a typical origin for a plural system to form in response to coping with traumatic and stressful events.

From a purely psychological standpoint, that is exactly what a plural system is for and why it exists.

Edited to add: I also want to say the experience you had– where you were aware, but someone else was acting– is an absolutely typical plural and/or dissociative experience.