You should NEVER try to fix an error message about a missing DLL by simply copying it into the program folder. Just consider all file operations in the program folder as TABOO. Sure, it might work but it's bad practice for a number of reasons. The proper way to handle such cases is to check if the icon you just clicked points to the right executable in the right location, and if it does, to take the error message as a hint that the installation is corrupt. Solution: Uninstall, reinstall.
Why is it bad practice?
Typically, after putting the first DLL into place, another error message pops up about another missing file
Corollary: If you "reinstall" your installation file by file until there are no more error messages, that doesn't necessarily mean that you fixed the installations. Maybe we just ran out of error messages. You could still get funky application behavior, and thus trigger a nightmarish support case.
DLLs are about as powerful as program files.
Would you accept "TotallyInnocent.exe" from an unknown source on your computer?
(Hint: The correct answer is: No!)
Not saying that Mark isn't to be trusted or had malicious intentions, but you could also ask Google for the file and find it "somewhere on the internet" and you just don't know who made it and for what purpose - both as far as declared intent goes, and undeclared. Don't invite vampires into your home!
Like program files, DLLs have versions. Just because two DLLs have the same name does not guarantee that they are of the same version. Different versions mean different functionality mean, possibly, funky application behavior with the resulting Support Case From Hell. (That's not just an unpleasant experience for me, but for you too)
Files that you drop manually into the program folder do not get uninstalled. Which may cause further trouble down the road, months later.