Yes, of course you can. Just install every one in a separate folder. Above version 67 there should be Dedicated profiles per Firefox installation created.

But what for do you need these multiple installations?

I am a link builder. Sometimes I get two or more projects in a same time. Then I feel trouble, because 2 different projects have different data. And those data must be separate from one to another. So I am searching 2 Firefox in same pc.

By doing your method, can I get a fully separate Firefox from my real one? Like Google Chrome account wise app

You don't need separate installations, you need only Multi-Account Containers.

Hey, Can you help me a little bit more? I need to use 2 fire fox account in a same time on same pc. Hows that possible?