I categorize this type of error as a "common error". In making the die(s) for stamping out (minting) the CICs, the bottom leg of the letter "E" has broken off and many (perhaps 100's, even 1000's of these CIC were stamped out and used.

This has happened on many CIC chips, just as Phyllis is showing another example.

So, in my opinion, while it is an error, many examples exist and any "variation" collector will have an interest in getting one, but not necessarily at a cost greater than the unblemished version.

Jim