As per the latest UGC guidelines, a student can pursue two full time degree courses at a time in Physical. So you can obviously do so. But you have to think the benefit out of it. If you are doing BA LLB then you are already getting a BA degree and if you go for the BA Hons in Political Science it will be nothing useful because if you are going for the BA LLB then you want to be a lawyer/Advocate right? So doing BA HOns in Political science and BA LLB can't be that much relevant to your career growth, but if you wish, you can always do that.

For more information regarding BA LLB consider the link below:

https://www.careers360.com/courses/ba-llb-dual-degree

I hope this helps. Wish you a great day!