First, is the second router connected to the same ISP? Then, are you connecting with two different systems through the two routers? And can you clarify if you are asking about two concurrent logins?
Finally, what does your ISP service agreement say about logging in as you’re trying to do? We’re not likely to know anything about agreements that you have.
last time when my friend tried that, it doesnt allow the other router to connect..so some might allow you to do concurrent login.