Hey could someone please tell me what is the word or synonym for "copying someone's pose, style , get up"?
"Copying" is in itself a way to describe that, but I imagine you're looking for something a bit more specific.
You could say that person is being your 'doppleganger", which is a good word for a double of someone, with a slight connotation to being an 'evil' double from its German roots.
Being a "copycat" is a common term used to describe when someone is doing the exact same thing you do in the exact same way.
The closest I can think of is copycat
cop·y·cat (kp-kt) Informal
One that closely imitates or mimics another.
v. cop·y·cat·ted, cop·y·cat·ting, cop·y·cats
To act as an imitator or mimic.
To imitate closely; mimic.
Closely imitating or following another: a copycat version of a successful product; a copycat crime.
Mirroring - is a psychological term to describe the behaviour in which one person copies another person usually while in social interaction with them. It may include miming gestures, movements, body language, muscle tensions, expressions, tones, eye movements, breathing, tempo, accent, attitude, choice of words or metaphors, and other aspects of communication. It is often observed among couples or close friends.