Hii, Im pretty sure this is not intended but in the current version there is a bug related to item mods, whenever I've put a mod on a piece of gear, that respective piece also appears as a new item in my inventory, practically duping it. Hope this helps ^.^
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It's actually a problem in 1.99 where entering the 'Learn Skill' menu, and then scrolling to other jobs, causes equipped items on that character to get 'duplicated' (in a manner of speaking, it's really more like two ways to get to the same item). This's been fixed in the 2.0 release that launched tonight!