If you add additional crafting resources into the crafting bench, and, before collecting your new items, select a different recipe. The crafting bench will only return the resources for one copy of the item.

For example:
If I select the Crafting Bench recipe, and pick up a stack of Wooden Planks, and Drag my LMB on top of the Crafting bench recipe to craft more at once, then select a different recipe, only 4 of my 68 planks would be returned to my inventory, deleting the other 64 I just added.