Can I use two separate accounts on two instances on the same browser?

Is it okay to set up two accounts for two instances on the same web browser? When I go to visit the first instance, i can see that account is logged in for that instance. So, that works. Then I direct myself to the another instance's community/post, I can see the 2nd account is logged in for that instance. Would it make sense for me to set up individual accounts for each instance, or should I stick with only one account?

I am not understanding this federverse I have been reading about as today is my first day. thank you