Washington Quater 1958D [gelöst]

I was putting some 1958 D quarters in flips and noticed what appears to be a D over D mint mark on several coins. I also found several with extra plumage on the back of the head. See the attached photos.



I even found a few that had both the extra plumage and the D over D mint mark. Are these errors and if so are they documented anywhere?

Thanks in advance!

https://www.usacoinbook.com/us-coins/1958-d-washington-quarter.jpg

I can see nothing unusual about your coin. Perhaps a little machine doubling if anything.

You can also try, http://www.varietyvista.com/
This site has helped me for many of my coins from Double Dies to RPM's

Verweis : "harryg"​https://www.usacoinbook.com/us-coins/1958-d-washington-quarter.jpg
​
​I can see nothing unusual about your coin. Perhaps a little machine doubling if anything.

​Thank you! Is machine doubling considered an error?

Verweis : "Ringgy"​You can also try, http://www.varietyvista.com/
​This site has helped me for many of my coins from Double Dies to RPM's
​
​

​Thank you for the link! I still a newbie so can you tell me what RPM stands for?

Repunched Mintmark

http://www.varietyvista.com/25%20What%20Are%20Die%20Varieties/The%20RPM.htm

Verweis : "johnmhamilton"​

Verweis : "harryg"​https://www.usacoinbook.com/us-coins/1958-d-washington-quarter.jpg
​​
​​I can see nothing unusual about your coin. Perhaps a little machine doubling if anything.

​​Thank you! Is machine doubling considered an error?

​https://www.ngccoin.com/news/article/5688/Double-Dies-vs-Machine-Doubling/