In the latest version I am unable to copy variables properly with some crafting interfaces. Using the personal 2x2 crafting area, or the vanilla workbench 3x3, I can place a stored variable and a blank, and it'll correctly show me a copy would be produced. When I pick up the copy though, it shows a red zero on it. Placing it in my inventory, it immediately disappears and the original variable gets picked up automatically. The copy is lost.

The copying works fine if I do it using the "duel crafter" of the NeoTech mod. My only guess at what the important difference is is that it works with crafting interfaces that can store items after you close the window, and fails for those that can't store items (like the vanilla one that just spits items into the world if you close the window).