No. Clear reports were heard and described by several witnesses in multiple attacks.
1. Single round per attack
a. Could be fire discipline, esp. if this is a trained attacker or terrorist
b. Could mean sniper is using a turnbolt, either long arm or something like a Contender
c. The brass picked up with the Tarot card was the only one reported. Was it a plant?
2. If the sniper is using a semiauto, he has to be using a brass catcher, and the brass discovered with the Tarot card is his, that got away somehow? If he's using a turnbolt weapon, the brass is probably a plant from another type weapon in .223 cal. If he's using a semiauto with brass catcher, then he is exercising fire discipline, and the brass may be a plant anyway.
3. If the sniper is planting misleading evidence, then confusion is a major goal, either to help him evade/escape, or because he's a terrorist.
4. If the sniper is using a semiauto like a CAR-15, then he is exercising fire discipline. Does that make him a trained terrorist?
5. Either way, he's a fanatic, taking huge chances.
That's as far as I want to go right now.
By the way, using two vehicles doesn't make sense. Why a two-man team? They couldn't communicate without being compromised by NSA, law enforcement, or someone else.