The phrase "legit copy" refers to a version or copy of something that is legal, authorized, and genuine. It means that the item or content is obtained or purchased legally, without any illegal or unauthorized actions. Full definition
This is silly, if you have purchased a DVD anywhere in the world you are entitled to watch it, its not breaching copyright laws etc as you have purchased a legit copy. (newscientist.com)
While the topic surrounding emulation also revolves around piracy, there is no doubt that it offers those who have a legit copy of the game to play their copies in a better resolution and image quality. (gearnuke.com)
And you might be saying «how can Sony know if you already own them», well, just like how the PS4 will only play legit DVDs, PS1 / PS2 disc support will only work if the disc is a legit copy and not a pirated one. (blog.us.playstation.com)