When you ctrl+middle mouse on a sign, it is supposed to give you a sign with the NBT tag of the original sign you selected. On this new snapshot, the signs aren't duplicated. Also, I switched my world back to 1.10.2 after I saw this, and all my signs disappeared. Only their black outlines are there when I hover over where the blocks used to be. Please help!
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Only affects a single sign item. It works correctly if you middle click a sign twice, stack the two sign items and then place them.
Confirmed. Clones MC-48503.