fix(Core/Loot): Fixed processing duplicated loot item within different groups. (#13038)

Fixes #13038

src/server/game/Loot/LootItemStorage.cpp

@@ -197,6 +197,7 @@ bool LootItemStorage::LoadStoredLoot(Item* item, Player* player)
             li.randomPropertyId = it2->randomPropertyId;
             li.randomSuffix = it2->randomSuffix;
             li.rollWinnerGUID = ObjectGuid::Empty;
+            li.groupid = 0;
 
             // Copy the extra loot conditions from the item in the loot template
             lt->CopyConditions(&li, it2->conditionLootId);

src/server/game/Loot/LootMgr.cpp

@@ -71,7 +71,7 @@ struct LootGroupInvalidSelector : public Acore::unary_function<LootStoreItem*, b
 
             uint8 foundDuplicates = 0;
             for (std::vector<LootItem>::const_iterator itr = _loot.items.begin(); itr != _loot.items.end(); ++itr)
-                if (itr->itemid == item->itemid)
+                if (itr->itemid == item->itemid && itr->groupid == item->groupid)
                 {
                     ++foundDuplicates;
                     if (_proto->InventoryType == 0 && foundDuplicates == 3 && _proto->ItemId != 47242 /*Trophy of the Crusade*/) // Non-equippable items are limited to 3 drops
@@ -401,6 +401,7 @@ LootItem::LootItem(LootStoreItem const& li)
     is_underthreshold = 0;
     is_counted = 0;
     rollWinnerGUID = ObjectGuid::Empty;
+    groupid = li.groupid;
 }
 
 // Basic checks for player/item compatibility - if false no chance to see the item in the loot

src/server/game/Loot/LootMgr.h

@@ -168,6 +168,7 @@ struct LootItem
     bool    is_counted        : 1;
     bool    needs_quest       : 1;                          // quest drop
     bool    follow_loot_rules : 1;
+    uint8   groupid           : 7;
 
     // Constructor, copies most fields from LootStoreItem, generates random count and random suffixes/properties
     // Should be called for non-reference LootStoreItem entries only (reference = 0)