Even though dumbbell work uses each arm independently, you can improve the effects of DB work by pressing one dumbbell at a time.
From the starting position of a dumbbell military or bench, hold the right arm extended as you take the left arm through the movement. Repeat on the opposite side by keeping the left arm extended and taking the right arm through the ROM. You can alternate arms, or if one side is significantly stronger than the other perform all the reps on the weak side before moving to the strong side. Not only will you prioritize your weak arm, you’ll pre-fatigue your stronger arm with the isometric hold.