I think you are confusing paper documentation for your legal status with airline paperwork. I-94 is a legal document which has nothing to do with airline agents (see this reference). It's endorsed by CBP agents upon your arrival/entry to the United States (source here).

If you have 3 I-94 cards, I assume you either have been in and out of the States 3 times or filed for extension before. I have had a handful of I-94 throughout the years and only the latest one is the "valid" one since that's the most recent legal documentation of my entry. I don't recall I have any "old" I-94 with me since it's always collected by the CBP upon my exit (I think). Not sure how you get to hang on to 3 cards.

I am on student visa. I don't know if the rules would be different to work visa holders. I would think it should be the same though. I mean the most recent one is the "official" one that counts.