

Does my doppelganger have the same knowledge I have, or just the same outward physical characteristics?
They don’t have a replica of your brain, if that’s what you are asking.
They just look the exact same as you, along with your voice.
But they might have hacked your phone and started listening in to be able to mimic the way you talk.
Does my doppelganger possess the same physical objects I do, like an identical copy of a cell phone, say?
No, but they could just steal your phone, or better yet, just kidnap you and lock you away then steal your clothes too.
Lol, I think passwords are very trival to get.
I mean, they got the ability to look like you, you gotta assume they can get CCTV footage of you typing your passwords.