Right on bro, because 2 pull ups are better than 1.
I would do as many sets of 2 as I could with just enough time to recoup for 2 more..
It won't take any time at all and you will be gaining reps.
Pull up's are hard I am at 10 reps looking for 12. Now if i can at 41yo 16%bf 6'3 262 pounds
so can you.