1.5.2 Stack size 0 and duping item on use error

Atm my code(as follows), when i use the editable items(non unfired or ceramic), will delete the original, give you the original back, plus 2 cups(its supposed to delete the one you eat, and remove it, and give you  single cup)

and when i try to craft the unfired mug and stack them, it doesnt, it deletes them, however in creative, if i spawn them in, they can be seperated and combined.

package vanityblocks.Items;
import java.util.Collection;
import java.util.Iterator;
import java.util.List;

import net.minecraft.client.renderer.texture.IconRegister;
import net.minecraft.creativetab.CreativeTabs;
import net.minecraft.entity.player.EntityPlayer;
import net.minecraft.item.EnumAction;
import net.minecraft.item.Item;
import net.minecraft.item.ItemFood;
import net.minecraft.item.ItemStack;
import net.minecraft.potion.Potion;
import net.minecraft.potion.PotionEffect;
import net.minecraft.util.Icon;
import net.minecraft.world.World;
import cpw.mods.fml.relauncher.Side;
import cpw.mods.fml.relauncher.SideOnly;
import vanityblocks.Registrations.GeneralFoodItemsRegistration;

/*
* To do, fix the duping crap upon eating one, figure out stack size problem
*/
public class ClayMugItem extends ItemFood
{
public Icon[] icons;
public String[] textureNames = new String[] { "unfired", "ceramic", "mugwithwater", "hotchocowater", "hotchocowatersweet", "mugwithmilk", "hotchocomilk" };

        public ClayMugItem(int id, int heal)
        {
                super(id, heal, 0.0F, false);
                setHasSubtypes(true);
                setMaxDamage(0);
                this.maxStackSize = 16;
  setCreativeTab(vanityblocks.VanityBlocks.tabCustom);
                //this.setAlwaysEdible();
        }
   
        public ItemStack onItemRightClick(ItemStack par1ItemStack, World par2World, EntityPlayer par3EntityPlayer)
        {
         switch (par1ItemStack.getItemDamage())
         {
         case 0:
          break;
         case 1:
          break;
         case 2:
          par3EntityPlayer.setItemInUse(par1ItemStack, this.getMaxItemUseDuration(par1ItemStack));
          break;
         case 3:
                        par3EntityPlayer.setItemInUse(par1ItemStack, this.getMaxItemUseDuration(par1ItemStack));
                        break;
         case 4:
                        par3EntityPlayer.setItemInUse(par1ItemStack, this.getMaxItemUseDuration(par1ItemStack));
                        break;
         case 5:
                        par3EntityPlayer.setItemInUse(par1ItemStack, this.getMaxItemUseDuration(par1ItemStack));
                        break;
         case 6:
                        par3EntityPlayer.setItemInUse(par1ItemStack, this.getMaxItemUseDuration(par1ItemStack));
                        break;
         }
                return par1ItemStack;
        }
   
        protected void onFoodEaten(ItemStack stack, World world, EntityPlayer player)
        {
         if (!world.isRemote)
         {
          int duration = 0;
          PotionEffect potion;
          if (!player.capabilities.isCreativeMode)
                {
                         --stack.stackSize;
                 }
          switch (stack.getItemDamage())
          {
          case 0:
                         player.inventory.addItemStackToInventory(new ItemStack(vanityblocks.Registrations.GeneralFoodItemsRegistration.claymugitem,1,1));      
           break;
          
          case 1:
                         player.inventory.addItemStackToInventory(new ItemStack(vanityblocks.Registrations.GeneralFoodItemsRegistration.claymugitem,1,1));      
           break;
          
          case 2:
                         player.inventory.addItemStackToInventory(new ItemStack(vanityblocks.Registrations.GeneralFoodItemsRegistration.claymugitem,1,1));      
           break;
          
          case 3:
           potion = player.getActivePotionEffect(Potion.regeneration);
           if (potion != null)
                duration = potion.duration;
           player.addPotionEffect(new PotionEffect(Potion.regeneration.id, duration + 8*20, 0));
                         player.inventory.addItemStackToInventory(new ItemStack(vanityblocks.Registrations.GeneralFoodItemsRegistration.claymugitem,1,1));      
           break;
          
          case 4:
           potion = player.getActivePotionEffect(Potion.regeneration);
           if (potion != null)
                duration = potion.duration;
           player.addPotionEffect(new PotionEffect(Potion.regeneration.id, duration + 8*20, 0));
                         player.inventory.addItemStackToInventory(new ItemStack(vanityblocks.Registrations.GeneralFoodItemsRegistration.claymugitem,1,1));      
          
           potion = player.getActivePotionEffect(Potion.moveSpeed);
           if (potion != null)
                duration = potion.duration;
           player.addPotionEffect(new PotionEffect(Potion.moveSpeed.id, duration + 8*20, 0));
                         player.inventory.addItemStackToInventory(new ItemStack(vanityblocks.Registrations.GeneralFoodItemsRegistration.claymugitem,1,1));      
           break;
          
          case 5:
           player.removePotionEffect(19);
//         potion = player.getActivePotionEffect(Potion.regeneration);
//         if (potion != null)
//              duration = potion.duration;
//         player.addPotionEffect(new PotionEffect(Potion.regeneration.id, duration + 3*20, 0));
                         player.inventory.addItemStackToInventory(new ItemStack(vanityblocks.Registrations.GeneralFoodItemsRegistration.claymugitem,1,1));      
           break;
           //"unfired"0, "ceramic"1, "mugwithwater"2, "hotchocowater"3, "hotchocowatersweet"4,
        //"mugwithmilk5", "hotchocomilk6" };

          case 6:
        player.removePotionEffect(19);
           potion = player.getActivePotionEffect(Potion.regeneration);
           if (potion != null)
                duration = potion.duration;
           player.addPotionEffect(new PotionEffect(Potion.regeneration.id, duration + 3*20, 0));
                         player.inventory.addItemStackToInventory(new ItemStack(vanityblocks.Registrations.GeneralFoodItemsRegistration.claymugitem,1,1));      
           break;
          }             
         }
        }
        public EnumAction getItemUseAction(ItemStack par1ItemStack)
        {
                return EnumAction.drink;
        }  
        @Override
        public int getMaxItemUseDuration(ItemStack itemstack)
        {
                return 24;
        }

@Override
@SideOnly(Side.CLIENT)
public void addInformation (ItemStack stack, EntityPlayer player, List list, boolean par4)
{
  //"unfired"0, "ceramic"1, "mugwithwater"2, "hotchocowater"3, "hotchocowatersweet"4,
  //"mugwithmilk5", "hotchocomilk6" };
//  list.add("A little bit evil");
         switch (stack.getItemDamage())
         {
         case 0:
          break;
         case 1:
          break;
         case 2:
          break;
         case 3:
          break;
         case 4:
          list.add("Gives you speed");
          break;
         case 5:
          list.add("Removes Poison");
          break;
         case 6:
          list.add("Removes Poison");
          break;
         }
}
@SideOnly(Side.CLIENT)
@Override
        public void registerIcons(IconRegister iconRegister)
        {
  this.icons = new Icon[textureNames.length];
                for (int i = 0; i < this.icons.length; ++i)
                {
                        this.icons[i] = iconRegister.registerIcon("vanityblocks:mug_"+textureNames[i]);
                }
        }
        /**
         * returns a list of items with the same ID, but different meta (eg: dye returns 16 items)
         */
        @SideOnly(Side.CLIENT)
        @Override
        public void getSubItems(int par1, CreativeTabs par2CreativeTabs, List par3List)
        {
                for (int var4 = 0; var4 < 7; ++var4)
                {
                        par3List.add(new ItemStack(par1, 1, var4));
                }
        }
        @Override
        public String getUnlocalizedName(ItemStack itemstack)
        {
                return (new StringBuilder()).append("item.mug.").append(textureNames[itemstack.getItemDamage()]).toString();
        }
        /*public boolean isPotionIngredient()
        {
                return true;
        }*/
}