My experience with these things would say "It depends". The staff at fast food restaurants are probably not going to give more than 15 seconds of thought to coupon redemption, however this is what it says for conditions:
"No purchase necessary. Coupon has a one-time only use. Cannot be combined with any other coupon or promotion. Limit one discount per coupon, one coupon per customer. "
I guess that doesn't stop you visiting multiple restaurants, or driving through drive-through 10x or having 4 people in the car, each with a coupon, etc. I wouldn't abuse it, and YMMV. But try it and let us know your results.
K