weird question about baby registry?

So I'm very newly pregnant (7w today) but I'm so excited about everything that I've started checking out registry items and what I should do for the baby extra. Which leads me to this question, do you put 1 baby car seat one the registry for one vehicle then you and your husband take that vehicle whenever you have the baby (like he'd take my car if he was taking the baby somewhere without me) or did you put two car seats on your registry? They're expensive, I just don't know what the norm is for this? I feel like if I only put one on there I'd buy a second one? Let me know your thoughts!