when you’re learning to hurdle with both legs, take your time. It’s going to feel very strange pulling your trail leg when using your off leg. Start off slow, get a really good warm up in. before you even do drills, stand next to a hurdle, lean on the wall or another hurdle or something, and just pull your trail over the top of the hurdle like you’re doing drills. But do it slowly at first. This will get you more loosened up.
Side note, always be sure when you’re hurdling off legged that you get your trail back to that “A” position with your knee up ready for that next step.