RELINK TO FILE and REPLACE CONTENTS should be updated to work better

The condescending attitude not needed. And I understand how Relink works, but then explain how Replace Contents works while you're at it...

Anyway, what are you trying to do that prevents you from just placing a new linked SO that links to the new file? Why do you need to duplicate what you have and then "replace"? What's the goal here?

What is a linked SO? It's a link to a file that exists on your computer, right? When you duplicate that SO in Ps, you're not duplicating it on your drive, right? You're just creating another instance of the SO which is linking to the file on your drive. If you replace the contents of one, of course it's going to replace the contents of ALL INSTANCES OF THAT LINKED FILE. That's exactly how it should work and i use the behavior all the time to get my work done. If you want to link to a new file, DON'T DUPLICATE THE LINKED SMART OBJECT IN PS. I'm sorry you're having such a difficult time understanding how smart objects work, but this is exactly how they should work because it allows me to get my job done much faster than if they didn't work this way.

Why would I duplicate in OS?? Also, why is Relink and Replace doing the same thing? Kinda redundant no?

OS is Operating System and yes, if you're replacing content, Ps will replace all content that links to the same linked file. It's working exactly as it should. 

No... it is not. OS?

In this case, Ps is working EXACTLY as it should.

You need to duplicate in the OS and relink to that file.