Is that a Fed rule, because under NCAA, either team my decline a penalty. There is no reason that they would -- and when both are accepted, all accepted lives balls fouls by Teams A and B will offset.
NCAA Rule 10.1.4:
ARTICLE 4.
If live-ball fouls by both teams are reported to the referee, the
fouls offset and the down is repeated (A.R. 10-1-4-I and VII). Any player who
commits a foul that mandates disqualification must leave the game.
Exceptions:
1. When there is a change of team possession during a down, and the team
last gaining possession had not fouled before last gaining possession,
it may refuse offsetting fouls and thereby retain possession after
completion of the penalty for its foul (A.R. 10-1-4-II-VII).
2. When all Team B fouls are governed by postscrimmage kick rules,
Team B may refuse offsetting fouls and accept postscrimmage kick
enforcement.
3. Rules 8-3-4-c and 3-1-3-g-3 (during a try or extra period after Team B
possession).
There is no option to decline half of a double foul unless there was a change of possession or PSK enforcement.