The way my workout is split is as follows: I do legs on Sundays which includes squats followed by deadlifts and then leg presses. On Mondays I do bi's and back. I do lat pulldowns, seated cable rows, and then I move on to doing curls. On which one of these days should i do the deadlifts?
If I were to do a split, I'd do the deadlifts on my "back" day, not the "legs" day.
Here's why: both squats and deadlifts are compound movements that are best done heavy. They both do a good job stimulating whole-body growth. In contrast, curls, lat pull-downs and cable rows are exercises that target less overall muscle, which is fine as supplementary movements but not as your main one. They also are generally done with lower weight and more reps.
Separating the squats and deadlifts ensures that you target the most muscle systems while allowing proper recovery for each one.
But regardless, it's generally best for beginners and intermediate lifters to follow a proper training plan such as Starting Strength or 5x5 rather than coming up their own random splits. It also sounds like you're only lifting on Sunday and Monday--if this is correct, you might get more mileage from spreading out your lifting days or simply lifting three times a week, spaced out, instead of two days back-to-back.
Your program varies from a lot of standard programs in that you are including both squats and leg presses. In the most popular strength training programs, squats are done every workout, and deadlifts are done every second workout, alternating with power cleans or rows. No leg presses.
So, there's nothing wrong with doing squats and deadlifts in the same workout, but perhaps not with the leg presses. You could also put some upper body work in between your squats and deadlifts to give your legs some recovery time.
Workout A could be squats, overhead press, deadlift. These work the posterior chain, spinal erectors, shoulders, upper pecs, and triceps.
Workout B could be your bis and upper back day. You could also do squats on this day if you had a rest day between Workout A and Workout B.