In the Championship game between the two teams on February 25, Bacuna pushed his head towards that of one of the assistants and was promptly sent off by the referee.
On Monday, his name featured in the Football Association's suspension list and it appeared that he would serve a three-match ban, but the governing body has now announced that it has doubled his ban.
A statement of their official website read: "He admitted a breach of FA Rule E3 in that his behaviour in or around the 94th minute of the game constituted violent conduct in circumstances where the standard punishment of three matches would be clearly insufficient.
"Following an Independent Regulatory Commission hearing, a three-match suspension was added to the sanction the player is already serving following his dismissal."
Having already spent one game on the sidelines, Bacuna is scheduled to return to the first-team squad for the home game with Queens Park Rangers on April 4.