Something like that was done by someone outside the U.S. mint and adds absolutely no numismatic value to it. Being that it's pre-1982, it's worth 2 cents for its copper content.
It's still only one cent. This is NOT a mint error.
This type of error of misstruck coins is called 'Brockage'. A Lincoln penny with this error is valued at $35.00
The U.S. Mint has never made a "Memorial" Kennedy half dollar. Many different society's have counter stamped & gold plated Kennedy half dollars an sold them as "Memorial" coins. The coins are considered altered and have no numismatic value.
Model designation
THey were made by crescent firearm company.
Lincoln cents with Kennedy's face counter stamped on them are novelty coins that have no numismatic value at all. Many different dates and mintmarks exist, but they are still only face value.
If it is in good shape, it could be worth thousands of dollars. Check with your local coin collector.
Coins that have letters and numbers added are common, but it does not add to the value of any coin and kills the collectible value of any coin. The value of your counter stamped Large cent is "Whatever you can get".
JFK has appeared counter-stamped on many Lincoln cents of different dates for a very long time, this is not done by the US Mint. The coins are usually glued to a card with "Strange Facts" between both presidents, they have no numismatic collectible value.
It was madein the1930s by J Stevens Arms Springfield Mass. ( Crescent was bought out by them in 1932) and the name changed to Crescent - Davis. Value can range from 100. to 500. depending on condition.
50-100 dollars
The coin is only one cent, the counter stamped date adds nothing to the value.