diff --git a/main.py b/main.py
index a6427d8..dc83e32 100644
--- a/main.py
+++ b/main.py
@@ -152,8 +152,16 @@ async def get_meal(meal_id: int, conn: sqlite3.Connection = Depends(get_db)) ->
     
     return meal
 
-@app.post("/meals/")
-async def create_meal(meal: meals.Meal, conn: sqlite3.Connection = Depends(get_db)) -> meals.Meal:
+def get_duplicates(items: List[meals.Person]) -> set[str]:
+    seen : set[int] = set()
+    duplicates : set[str] = set()
+    for item in items:
+        if item.id in seen:
+            duplicates.add(item.name)
+        seen.add(item.id)
+    return duplicates
+
+def validate_meal(meal : meals.Meal) -> JSONResponse | None:
     if not meal.chefs:
         return JSONResponse(status_code=400, content={'message': 'Meal must have at least one chef'})
     
@@ -165,6 +173,26 @@ async def create_meal(meal: meals.Meal, conn: sqlite3.Connection = Depends(get_d
     
     if len(meal.recipes) == 0 and len(meal.extra_ingredients) == 0:
         return JSONResponse(status_code=400, content={'message': 'Meal must have at least one recipe or ingredient'})
+    
+    duplicates = get_duplicates(meal.chefs)
+    if duplicates:
+        return JSONResponse(status_code=400, content={'message': f'Duplicate chef: {", ".join(duplicates)}'})
+    
+    duplicates = get_duplicates(meal.cleanup)
+    if duplicates:
+        return JSONResponse(status_code=400, content={'message': f'Duplicate cleanup person: {", ".join(duplicates)}'})
+    
+    duplicates = get_duplicates(meal.consumers)
+    if duplicates:
+        return JSONResponse(status_code=400, content={'message': f'Duplicate consumer: {", ".join(duplicates)}'})
+    
+    return None
+                            
+@app.post("/meals/")
+async def create_meal(meal: meals.Meal, conn: sqlite3.Connection = Depends(get_db)) -> meals.Meal:
+    validation_response = validate_meal(meal)
+    if validation_response:
+        return validation_response
 
     await meals.insert_meal(conn, meal)
     await conn.commit()
@@ -178,6 +206,10 @@ async def update_meal(meal_id: int, meal: meals.Meal, conn: sqlite3.Connection =
     existing = await meals.find_meal_by_id(conn, meal_id)
     if not existing:
         return JSONResponse(status_code=404, content={'message': 'Meal not found'})
+    
+    validation_response = validate_meal(meal)
+    if validation_response:
+        return validation_response
 
     await meals.update_meal(conn, meal)
     await conn.commit()
diff --git a/tests.py b/tests.py
index 342b572..bdc87e0 100644
--- a/tests.py
+++ b/tests.py
@@ -1,7 +1,13 @@
 import unittest
-import test_data
 import datetime
 
+import test_data
+import importlib
+
+def reload_test_data():
+    global test_data
+    test_data = importlib.reload(test_data)
+
 import pathlib
 from db import connect, create
 
@@ -20,6 +26,7 @@ class TestProducts(unittest.IsolatedAsyncioTestCase):
     async def asyncSetUp(self):
         self.conn = await connect('./testdb.db')
         await create(self.conn)
+        reload_test_data()
         return await super().asyncSetUp()
 
     async def asyncTearDown(self) -> None:
@@ -49,6 +56,8 @@ class TestRecipe(unittest.IsolatedAsyncioTestCase):
         self.conn = await connect('./testdb.db')
         await create(self.conn)
         await test_data.create_persons(self.conn)
+        reload_test_data()
+
         return await super().asyncSetUp()
 
     async def asyncTearDown(self) -> None:
@@ -113,6 +122,7 @@ class TestMeals(unittest.IsolatedAsyncioTestCase):
         self.conn = await connect('./testdb.db')
         await create(self.conn)
         await test_data.create_persons(self.conn)
+        reload_test_data()
         return await super().asyncSetUp()
 
     async def asyncTearDown(self) -> None:
@@ -120,6 +130,48 @@ class TestMeals(unittest.IsolatedAsyncioTestCase):
         pathlib.Path('./testdb.db').unlink(missing_ok=True)
         return await super().asyncTearDown()
 
+    async def testMultiplePariticpants(self) -> None:
+        meal = test_data.Meals.broccoli_soup_for_jacob
+        recipe = meal.recipes[0]
+        recipe_ingredient = recipe.ingredients[0]
+        recipe_product = recipe_ingredient.product
+        extra_ingredient = meal.extra_ingredients[0]
+        extra_product = extra_ingredient.product
+
+        person = test_data.Persons.jacob
+
+        await products_db.insert_product(self.conn, recipe_product, {})
+        await products_db.insert_product(self.conn, extra_product, {})
+
+        created_recipe = await main.create_recipe(recipe, self.conn, person)
+        recipe.id = created_recipe.id
+
+        meal.chefs = [test_data.Persons.ryan, test_data.Persons.chris, test_data.Persons.ryan]
+        error_response = await main.create_meal(meal, self.conn)
+        self.assertIsNotNone(error_response)
+        self.assertEqual(error_response.status_code, 400)
+        self.assertEqual(error_response.body, b'{"message":"Duplicate chef: Ryan"}')
+
+
+        meal.chefs = [test_data.Persons.ryan, test_data.Persons.chris]
+        meal.consumers = [test_data.Persons.ryan, test_data.Persons.chris, test_data.Persons.ryan]
+        error_response = await main.create_meal(meal, self.conn)
+        self.assertIsNotNone(error_response)
+        self.assertEqual(error_response.status_code, 400)
+        self.assertEqual(error_response.body, b'{"message":"Duplicate consumer: Ryan"}')
+
+        meal.consumers = [test_data.Persons.ryan, test_data.Persons.chris]
+        meal.cleanup = [test_data.Persons.ryan, test_data.Persons.chris, test_data.Persons.ryan]
+        error_response = await main.create_meal(meal, self.conn)
+        self.assertIsNotNone(error_response)
+        self.assertEqual(error_response.status_code, 400)
+        self.assertEqual(error_response.body, b'{"message":"Duplicate cleanup person: Ryan"}')
+
+        meal.cleanup = [test_data.Persons.ryan, test_data.Persons.chris]
+        response = await main.create_meal(meal, self.conn)
+        self.assertIsNotNone(response)
+        self.assertIsInstance(response, meals.Meal, msg=response.body if hasattr(response, 'body') else response)
+
     async def testCreateAndFind(self) -> None:
         meal = test_data.Meals.broccoli_soup_for_jacob
         recipe = meal.recipes[0]