Sometimes a new collector will look to hard to find an error, Wexlers site will help you add a few resourses for errors and basic knowledge on how coins are made and how the oddities of errors and varieties are made I encourage you to check it out. https://doubleddie.com/58201.html
The Ming Dynasty was a long, long, time ago. It ended 304 years before this coins date, to be exact. I doubt that this piece was Minged to begin with.
Don't let these guys discourage you by having their fun at the expense of a typo. Yes, it is post mint damage. On the other hand, with the price of silver these days, your dime is still worth silver melt of over $3.55 as I write this.