I found this 1959 old one penny coin and noticed that the first 9 is a large and the second one is a small date 9! How could it happen?
Understanding how dies are made, is the key to knowing that you don't have a large 9 and a small 9 on the same coin. The Mint starts with a Master Hub, which is used to make Master dies, which are used to make working hubs, which are then used to make lots of working dies. The working die strikes the coin. The date is added before the working die step, so if they used a different size/style for the numbers, it would be on many dies and therefore, a whole lot of coins. The people answering your post are knowledgeable of the minting and die making process. That's why they can correctly say that your coin is not an error or variety.
Actually, I did check in coin selling sites for 1959 and I noticed a lot of coins like that almost all of them except a few!
I have a 1959 D penny with different sizes 9s too. The top of the first 9 is level with the tops of the 1,5, and other 9. Only difference is the tail of the first 9 extends a noticeable difference lower than the tail of the second 9.
The point is that the tip of the first nine head is pointing south east but in second nine the tip is pointing just east!
Wasn't it made clear that your coin does not have two different styles of 9. As posted previously, the date IS NOT punched into the individual working die. If you still believe you have something, please provide a plausible explanation of how it could occur during the die making process. Time to stop spreading misinformation. This is the reason members are critical of your follow up posts. They do nothing but confuse new collectors. Please stop it.
A number of things could have happened that give the coin this appearance. But I gotta tell you, you said “1959 old one penny coin”. I was born before 1959 so what does that make me, old?? I should think not.