Do upgraded weapons persist if I sell / drop the item?

In Deus Ex: Human Revolution, if I upgrade a weapon using one of the upgrade items, such as a suppressor or an ammo-capacity upgrade, etc., then I either sell the weapon, or drop it. Do all weapons of the same type subsequently have the upgrade?

For possible bonus points: Do all weapon drops of the same type from enemies have the same attributes?

Solution 1:

No - the weapons and items in Deus Ex: Human Revolution are unique - if you upgrade a weapon and then subsequently drop your weapon and find another of the same type, it will be a standard instance of the weapon with no upgrades.

If you go back to where you dropped your weapon and pick it back up, the weapon that you pick up will have the same upgrades as when you dropped it.

In the event that you sell a weapon, buying it back will purchase a standard instance of the weapon with no upgrades.