As @Patman64 suggered i taked a look at IsNoStackSpellDueToSpell.

Found that it compare spell 11305 and 30918.
Both are not passive. The function fail at isModifier test; after some more research i tested this patch and it work.
Not sure if its the good way, if so all AURA_MOD_XXX could also be assumed as a modifier. So it need a better patch with switch case or something like that what your thought?

src/game/SpellMgr.cpp

@@ -2131,8 +2131,10 @@ bool SpellMgr::IsNoStackSpellDueToSpell(uint32 spellId_1, uint32 spellId_2) cons
         {
             if (spellInfo_1->EffectApplyAuraName[i] == SPELL_AURA_ADD_FLAT_MODIFIER ||
                     spellInfo_1->EffectApplyAuraName[i] == SPELL_AURA_ADD_PCT_MODIFIER  ||
+                    spellInfo_1->EffectApplyAuraName[i] == SPELL_AURA_MOD_INCREASE_SPEED ||
                     spellInfo_2->EffectApplyAuraName[i] == SPELL_AURA_ADD_FLAT_MODIFIER ||
-                    spellInfo_2->EffectApplyAuraName[i] == SPELL_AURA_ADD_PCT_MODIFIER)
+                    spellInfo_2->EffectApplyAuraName[i] == SPELL_AURA_ADD_PCT_MODIFIER ||
+                    spellInfo_2->EffectApplyAuraName[i] == SPELL_AURA_MOD_INCREASE_SPEED)
                 isModifier = true;
         }