The situation you describe is considered to be a double foul.  Rule 9-7 Penalty 2b applies:
	Quote:
	
	
		| RULE 9 SECTION 7 PENALTY 2. For a double foul during a: a. Live-ball play, a replay is called;b. Dead ball, the penalty is assessed against the serving team followed by the receiving team with both teams rotating.
 | 
	
 Therefore, at the beginning of the set, a red card is shown against the serving team resulting in a penalty loss of rally.  The receiving team receives a penalty point and rotates.  Then, a red card is shown against the receiving team resulting in a penalty loss of rally.  The serving team receives a penalty point and rotates to serve with the score tied at 1-1.  The set continues from that point.