Thought this was pretty funny, also reported it as a glitch on Github:
I was building my house with my friend in the same room as me, then I heard footsteps from another room. Thought it was weird because that room is closed off… But then I saw a guy through the wall. Freaked out - was ready to kill the guy, then realized that it was my friends… twin? Odd. Check out the video. The twin mimics the same movements.
My friends had two versions of himself online at the same time. Also, he himself couldnt see his twin, but could hear echoing footsteps as if someone was running with him. Whenever you would try to access a box, it wouldn’t let him because the twin wasnt close enough. Also, when trying to place objects down, it wouldn’t place them where he was, but whatever direction the twin was facing.
Edit: We werent able to recreate the bug.