I believe you can only play one intelligence reaction card per offensive. You can play more than one attack card like the attrition strategy cards or the submarine card, checking the H1 recon graphic under the OC value, it's not an attack card, it's a card that changes the intelligence condition. IT just so happens to include an attack as a bonus.
The offensives sequence of play states:
Step 7. The Reaction player attempts to change the Offensive’s Intelligence Condition by playing an appropriate Reaction card or, as an alternative, making an intelligence die roll (7.25).
Note the use of the singular. This implies you play just one card to alter the intelligence condition.