NGC ERROR 0

[PAUL G...]

Is a 1964 D Kennedy Half Dollar in a NGC 1964 P (plain) holder worth a premium for the error? It is MS 66 and it checks out the holder has not been tampered with because the picture on the NGC website clearly shows a 1964 D in a 1964 P holder.

[Just Bob]

Somewhere out there in this big ol' world, there is bound to be someone who collects slab errors, including those that are mislabeled. They might be willing to pay a bit of a premium for it. But, as a general rule, no, it isn't worth more.  It may actually sell for less than a normal one, since a buyer would have to pay shipping costs to have it relabeled. 

[Coinbuf]

This is often called a mechanical error as someone typed the info incorrectly when creating the label, happens more often than you might think at all the TPG's.  There might be collectors that would place a small premium for this and while I wouldn't think it would be much collectors surprise me all the time on what and how much they are willing to pay for some things.