Plenty of Acuras came with red keys. Once they started doing the embedded chips they provided the red keys as "master keys."

I don't think thy were supposed to be used to start the car. If I remember correctly, they had all the transponder info in them and were used to program new keys in the event of lost keys. It's apparently nearly impossible to get new keys made if you've lost your red key without spending hundreds of dollars on new transponder stuff.