Are both of these slope designs genuine?
I am reasonably certain that this is just a mold change at some point, but it doesn't hurt to ask. I also have two textured types in dark blue, and one smooth type in sand blue.
It looks like it could be either #3049 or #3049c. Part #3049 currently exists in Sand Blue in at least three sets. As for the change in smooth and rough texture you may wish to read this answer by Joubarc.