Sentry Turret & Auto Turret + Global sales

Hey!

Great plugin David, but I have two questions:

1. I would like to sell the regular turret and also the Better Sentry Turret by Razor in your shop.
Since the Sentry is built as a skin for the regular turret, im not able to add both since one gets removed automatically from the list, probably because its regarded as a duplicate item. 

Could you explain how i can accomplish this, or update the plugin with the possibility to add same item more than once? Maybe that way i could add the default turret and the skinned turret.

2. I have the global sales permissions set up, however there is one category in the shop that i dont want to discount at all, can i exclude it from the permission somehow? 

Thanks!