This is minutia. Nothing I'd worry about as a beginner, really.
Now, for most people it is true that they can perform more reps and heavier weights with a parallel or supinated grip instead of a pronated one. I assume you are not an advanced bodybuilder who needs to strictly isolate his lats, so you can go ahead and use supinated grip.
I personally don't pull like that because I have a history of biceps-tendon injury so for me it's less painful to pull with a pronated grip.