the vast majority of people are going to be held back by an off hand. with ddkk/kkdd it's especially relevant.
can't really think of any map, but just try to find maps with those patterns/streams you have trouble with, like kk streams, and make sure its a bpm you are comfortable with. use half-time if necessary.
if you're still struggling try something even slower. the goal should be to get the general movement down, and then slowly push your speed, and adjust whatever technique you got as you go and play faster and faster maps.
with that being said, your off hand will most likely always be your off hand. it's perfectly fine if you can't do the speed with it that you can with your dominant hand.