Karl--you could turn out to be right. I hope not

.
The same issue exists on the 67 Punch Outs. Like the Plaks, SCD had a checklist but no one had ever found several of cards with listed captains. They then changed the listing to say the missing captains likely did not exist. Then one of the missing captains showed up. I think Mays, which may have been a prototype like the Robinson 3D. I think Larry here got that. So my completed set may be one short.

. Unless the Mays was a prototype, in which case it could be viewed as separate from the set, like the Robinson.
I think Bob and Larry have both also completed the 67 Stand Up set. I am still 3 short on that one
Bob-- those Dice cards look great. You should post a couple of your 70 cloth.