Dictyota or Sea Lettuce?

[Northlandboy]

I've got some algae starting on a few rocks. I purchased Sea Lettuce macro algae 8 weeks ago from Algae Barn, so I'm wondering if that stuff has the ability to frag and grow elsewhere on its own readily, or if this newly emerged stuff is perhaps a green shade of Dictyota.

Do I keep it in place , or scrub rocks to remove?

Thanks For any help!​

 

[Justdrew]

Dictyota normally shows branching behaviors. Don't see that yet, but not very tall either.

 

[Garpgarp]

Looks similar to what's presumably Ulva growing in my own tank that only had that and dry rock in.