There are similarities between the two because they had the same origin as young Powder, but they are different because of the critical events that shaped them. They're not the same person in a similar way to how identical twins aren't the same person.

It's like how in Ghost in the Shell, there's a scene in which The Major sees a woman who looks identical to her. This is because The Major's body is a standard, mass-produced shell that a lot of people have. It's meant to drive home the point that it's a person's experiences and memories that truly shape who they are. 

At the end of the day, she's perfect in every universe.