I have had the DC card since it started.
About a year ago, I forgot my DC card, but had my MKC on hand when I was making a purchase at TDS.
They allowed the MKC discount, but confiscated the card then and there.
And I saw this happen to someone else at TDS too.
So at least here, that was what was happening last year.
And mine had an expiration of 02/02 on it.