"this type of error" is not uncommon. This is a mis-matched inlay error. It is the same as a $5 inlay on a $25 check, or any other type of wrong inlay being affixed to one side of a chip.

With respect to errors in general, this type is not uncommon, but that does not mean that it is common. Although, it could be quite common and the Quality Control element is highly effective in removing (and destroying) such mistakes.

Jim