Lets say I have a page saved onto my computer from another website. The website deletes that page from their website and never returns it. One month later I put the content article on my page. Will I get hit with duplicate content penalty?
That shouldn't be duplicate if your page is a different domain name than the previous page that had the content.
No it will not be considered duplicate content because after a month Google should see that the page of that site no longer exists and you are free to use it on your site.
Technically not, but ethically it is. What about the people you have read the article? And what if others also start doing like this!! It's not copying rather theft.