In 14w05b, placing two tools/armor pieces/weapons into a crafting grid and trying to shift-click them out results in ~30 of that item flying out of the crafting table.
This glitch can be repeated multiple times to create infinite items for cheap.
Linked issues
duplicates 1
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Comments 3
I did not find the original report while submitting this. The keywords I used while searching were "Duplicate, Item and Crafting".
23 results, 10 (including your's) describing this issue: https://bugs.mojang.com/issues/?jql=text%20~%20%22Duplicate%20Item%20Crafting%22
43rd Duplicate of MC-46715 - If you have not, please use the search function in the future, to see if your bug has already been submitted. If you could not find the original report, please comment with the keywords you searched for.