As many have already said, Zane’s problem is a strange scaling of the hero’s abilities. There is another strange thing that hides behind this scaling, but affects the resulting DPS no less, and maybe more.
Digi-clone normally shoots, reloads, and immediately shoots, as it should. AI works true, there is no delay after reloading.
The problem appears with “Double Barrel”. If everything worked as with a normal clone’s weapon, then with “Boom. Enchance.” and “Mr Caffeine Shield” can get ~ + 140% reload speed for the clone. This could significantly accelerate the rate of fire for weapons with one_shot_mag_size, such as Scourge, Crossbow, Hellwalker, and very honestly.
Unfortunately, “Item Duping” is somehow buggy, or something else. After reloading the weapon, the clone is paralyzed for a short time. As a result, he shoots almost at the speed of the player without reload bonuses, when he could shoot from Crossbow like a machine gun. There is a feeling that he seemed to take out a new weapon every time the store is empty. May be it linked with handling. It looks like a bug that can be easily repaired and greatly strengthen the passive.