Fixes a bug in multi-item salvage

src/main/java/net/knarcraft/blacksmith/util/SalvageHelper.java

@@ -72,12 +72,28 @@ public final class SalvageHelper {
         }
 
         //Make sure to give salvage for all items if a stack > 1 is provided
-        List<ItemStack> salvage = new ArrayList<>();
+        List<ItemStack> allSalvage = new ArrayList<>();
         for (int i = 0; i < salvagedItem.getAmount(); i++) {
-            salvage.addAll(getSalvage(ingredients, salvagedItem));
+            allSalvage.addAll(getSalvage(copyItems(ingredients), salvagedItem));
         }
 
-        return combineStacks(salvage);
+        return combineStacks(allSalvage);
+    }
+
+    /**
+     * Copies a list of items
+     *
+     * <p>Note: This does not copy any metadata. It only copies the item type and the amount.</p>
+     *
+     * @param itemsToCopy <p>The items to make a copy of</p>
+     * @return <p>A copy of the given items</p>
+     */
+    private static List<ItemStack> copyItems(List<ItemStack> itemsToCopy) {
+        List<ItemStack> copies = new ArrayList<>(itemsToCopy.size());
+        for (ItemStack itemStack : itemsToCopy) {
+            copies.add(new ItemStack(itemStack.getType(), itemStack.getAmount()));
+        }
+        return copies;
     }
 
     /**