Do you keep things equal between all kids?

I have 2 step kids, 12 and 13. When it comes to snack foods and dinners I always make sure to get what each of them loves. However sometimes when I’m out shopping I see something for step daughter I want to get her so badly! But then feel obligated to also find something for my step son which becomes stressful. Or vice versa with them. My husband used to always buy them each something or each nothing to “keep it fair”. I think now they’re old enough to realize they won’t always get the same things whenever. Example, my daughter needed a case for her camera and I got her one. Only $12. My son didn’t say anything about it but I still felt bad. Of course if he needs something I get it also. Is it okay to get them things without getting the other something? It’s never big stuff. Just clothing items or stuff for their bedroom.

EDIT:

Obviously I’m not meaning things like candy or food. If I see a bra discounted that I want to get my step daughter, I don’t see the reasoning to also get my step son something at a similar price that he probably won’t even care about or use. And I usually just lay the item on their bed so the other doesn’t see it or care. Just like I’m not going to get them both a car when my son turns 16. In the end it comes out equal and they’ve never said anything about it to us.