This kind of error has been appearing more now than usual on Coin Talk.. This is what is called a Die Break or Chip. So it would be referred to as a "BIE" error. Because it looks like LI"BIE"RTY. What you have is known also as a half "BIE" because it was not fully formed. It is fairly common in Cents minted in the 50's and 60's. When the die is overused after striking many coins it gets brittle in certain spots especially on the date and the word LIBERTY. And as your example on the Reverse side above the letter E. Nice one!
Very odd coincidence happening on both "E"s. I agree with the above, they are both die cracks, the one on the front and is a "BIE" die chip
