I found a 1966 penny, in remarkably good condition for a circulation coin, but I am unsure whether what I see is anything at all. The lettering seems to be thicker than usual. For comparison I will include a picture of a similarly good conditioned 1969 penny. Unsure probably nothing but let me know thanks!
Welcome to Coin Talk. Sometimes thick lettering and numerals are caused by a worn die. In certain cases it may be an indication of some kind of doubling. DD-doubled die; MD-mechanical doubling; DDD-die deterioration doubling. There may be other reasons but I don't know them all. From your photos I can't see any doubling.
Your '66 coin and the '69 coin were produced using two different Master Dies. They really can't be compared to each other. In 1969 the mint started using a new master die. This made a major difference on how the coins look. Here is a side by side for comparison.
I think the next change came in as early as 1972. 1969 is a popular year for the floating roof reverse.
I think the difference your seeing is based on two things. A change occurred between the dates on both coins and older, worn dies produce what you see on your 1966 cent. Welcome to CT.
This is the first time I have seen the floating roof coin mentioned in a while. I have one of the 1969 ones and it is the only one I ever found. Plus the floating roof on my coin the top of the memorial pillars are slanted and sharp on the left side of the top of them.
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