As you can see that while they do look very similar in the bottles they are different on the nail. Purple Yourself together is a lighter purple with a strong gold shimmer that does not hide. It also has a thinner formula which results in needing three coats to be fully opaque. Dutch'ya Just Love OPI? is a darker purple and has a more pigmented formula which required only two coats to be fully opaque. Possibly because it is so pigmented, the shimmer does not show up as much as in Purple Yourself Together.
Index and Ring fingers: OPI Duch'ya Just Love OPI?, 2 coats (no top coat)
Middle and Pinkie fingers: Nicole by OPI Purple Yourself Together, 3 coats (no top coat)
Another bottle shot to show how similar they look in the bottle...
Both polishes are gorgeous...
Hopefully this was a useful comparison! Let me know what you think of this :)
Thanks for looking!