While you are destroing a block, and change from for example wood to wood planks, level of destruction will go to zero again.
1. Start breaking block, while holding item1
2. Change from item1 to item2
MC-1982
Breaking blocks
Resolved
Duplicate
0
Oskar Grzybek
(Unassigned)
Unconfirmed
Minecraft 1.4.3
Retrieved
Yeah I have noticed this too.But I don't know if this is intended because there was a duplication glitch that was using this method.