some blocks duplicate/disappear when mined

When you mine a furnace you either get two furnaces or no furnaces. Unaffected by silk touch. Ender chests meanwhile drop 8 obsidian when mined without silk touch whereas with silk touch it will drop an ender chest and 8 obsidian. I also found that cocoa pods when not mature drop 2 beans. Cauldrons drop 2 couldron items instead of 1.