  We consider simulation games played between Spoiler and Duplicator on two
B\"uchi automata in which the choices made by Spoiler can be buffered by
Duplicator in several buffers before she executes them on her structure. We
show that the simulation games are useful to approximate the inclusion of trace
closures of languages accepted by finite-state automata, which is known to be
undecidable. We study the decidability and complexity and show that the game
with bounded buffers can be decided in polynomial time, whereas the game with
one unbounded and one bounded buffer is highly undecidable. We also show some
sufficient conditions on the automata for Duplicator to win the game (with
unbounded buffers).
