I don't remember where I heard it but it seems very plausible given all of the other out of spec things Ludwig has done over the years such as Supras with Bowtie lugs, Blackros with Imperial lugs. When I say "fair number" I am referring to a fair number of the 8 lug Supras survived. I have no idea what the actual number is but I have heard of 8 lug Supras and I think I have seen pictures or auctions for one or two.
It would be a very easy mistake to make. The shell vender delivers a load of prepunched Supra and Acro shells. Either the supplier mislabeled a pallet or two of shells and a Ludwig employee didn't catch the mistake, they get polished and sent to the plater. Or some new Ludwig employee makes a mistake and gives the guy at the polishing machine Acro shells rather than Supra shells. I would guess that the number was probably high enough that The Chief or Sr didn't want to throw them all out so made the decision to send them out and deal with any complaints if they came in. Obviously not a very high number because these things are definitely not common.
There is a home movie that The Chief took in '64 and a factory tour from the last 10 years or so that show the exactly same thing happening to Supra shells. Shells with holes already punched in them are polished on a massive buffing machine. The worker holds a pipe through the shell to allow it to spin against the buffing wheel as the shell is polished. I don't think Acro shells wouldn't need to be polished because they didn't get plated, although the early keystone ones might have been due to their shinier finish, but looking at a raw Supra shell and a raw Acro shell, the only thing that sets them apart is the number of lug holes...
Quite a number of scenarios can lead to someone making a mistake and the economics of scrapping the shells, the disruption to the output of Supras could easily explain why there are any 8 lug Supras.