What is the legal ruling on employees selling and dividing "pharmacy cartons," and what should an employee do if there is a dispute regarding this division?

The default rule is that pharmacy cartons belong to their owner, and it is not permissible for an employee to sell them except with the owner's permission.

If the owner permits their sale, they belong to the one he permitted. If he discards them, or if the custom is to discard them, then they belong to whoever takes them; because customary permission is like explicit permission.

Everything that people discard due to disinterest, or that which the soul does not desire, then whoever reaches it first has a greater right to it; based on the Prophet's (peace and blessings be upon him) saying: “Whoever precedes to something that no Muslim has preceded him to, then he has a greater right to it.”