Of course, I have to do my usual "it's purple, so it's not color accurate" disclaimer, but I'm pretty sure you can still see the difference in the 2 colors.
Bottle on the left is Mimi. Bottle on the right is Julieanne.
L-R: Mimi, Julieanne, Mimi, Julieanne. Please enlarge to see detail.
As you can see, they are both purple and sparkly, and both have some form of golden shimmer, but after that, the similarities end. Mimi has a grape base and more vibrant shimmer, whereas, Julieanne has a charcoal base and more subtle (though still sparkly) shimmer. The golden shimmer in Mimi is more of a bright gold and the gold in Julieanne is more of a burnished gold. Julieanne is a much more complex color than Mimi, but they are both beautiful. Bottom line, if you love purples... yes, you need both.