Fixing a new duping bug. And this time it was NOT our fault!

src/main/java/com/gmail/nossr50/listeners/BlockListener.java

@@ -87,7 +87,7 @@ public class BlockListener implements Listener {
     public void onBlockPistonRetract(BlockPistonRetractEvent event) {
         if (event.isSticky()) {
             //Needed only because under some circumstances Minecraft doesn't move the block
-            plugin.getServer().getScheduler().scheduleSyncDelayedTask(plugin, new StickyPistonTracker(event), 0);
+            plugin.getServer().getScheduler().scheduleSyncDelayedTask(plugin, new StickyPistonTracker(event), 2);
         }
     }
 

src/main/java/com/gmail/nossr50/runnables/StickyPistonTracker.java

@@ -15,13 +15,16 @@ public class StickyPistonTracker implements Runnable {
 
     @Override
     public void run() {
-        Block originalBlock = event.getRetractLocation().getBlock();
+        Block newBlock = event.getBlock().getRelative(event.getDirection());
+        Block originalBlock = newBlock.getRelative(event.getDirection());
 
-        if (originalBlock.getType() == Material.AIR && mcMMO.placeStore.isTrue(originalBlock)) {
-            Block newBlock = originalBlock.getRelative(event.getDirection().getOppositeFace());
+        if (originalBlock.getType() != Material.AIR)
+            return;
 
-            mcMMO.placeStore.setFalse(originalBlock);
-            mcMMO.placeStore.setTrue(newBlock);
-        }
+        if (!mcMMO.placeStore.isTrue(originalBlock))
+            return;
+
+        mcMMO.placeStore.setFalse(originalBlock);
+        mcMMO.placeStore.setTrue(newBlock);
     }
 }