New. Any Help Would Be Appreciated

Hey guys, I just started to collect errors and varieties recently. Basically collecting what I can find in rolls and pocket change for now. I'm hoping that I can get a little help from you all. So far, I haven't run into much, although I did get a Buffalo nickel in some pocket change. The date and most of the lettering was worn completely off, but I'm keeping it nonetheless.
I have a couple of pictures, and if anyone can look at them and clarify a couple of things, I'd greatly appreciate it.




This is the first one. As you can see, there is some slight doubling on the 6 at the green arrow. I'm assuming this is either PMD or Mechanical Doubling. There is also something at the red arrow. I'm guessing this is resulting from a broken die, maybe. Being new, I'd hate to throw something out that I might be able to add to my new collection.



This second one is what I believe to be a repunched mint mark. It looks to me like there is a very pronounced D over a second mark.
These repunched marks are giving me fits, as a lot of the marks I'm seeing on the older coins are not as clear as the modern coins. Any thoughts on this one?

Thanks for taking the time to read and I do appreciate the responses. I wish you all a great day.