Phone and watch duplicate steps?

Hi all.... Planning to buy galaxy watch 4 classic Got a used one for $50 and seems like a good deal? Anyhow I use my phone Samsung galaxy s health app to count my steps and workouts, I am buying this watch to get more accurate readings and to not hold the phone all the time but I will still have it with me

I worry that my phone might double count steps and workouts? Is that a possibility or known issue? Or does the phone communicate with the watch and only 1 of them counts Thanks