to spare time away from one's main activity

doppelganger; doppelgänger -- a person's double

a sockpuppet (usu. 假分身) -- an internet account which was created in forums or comments for the purpose of falsely appearing as an outside supporter of a person or organisation when in fact it may be the same person/organisation himself/themselves.

have no time (for sth); be too busy (to do sth)