SECOND Job Stones for base classes of ARR?

[Garnix]

First: They'd share the same weapon. Secondly: they wouldnt need to develope a whole new job. It would be more like the same base class / job with a refreshing new twist / spec.

They wouldn't though.
SMN and SCH both use books. But not the same books.
WHM and BLM both use two handed staves despite being different classes.
So both jobs could have a bow without having the same base class.

To be honest though, I also want a Ranger job. But I kinda want it to get a crossbow instead of a bow.

Edit: and as proven by SCH and SMN, your second point is not valid. The two jobs have nothing in common anymore.