diff --git a/backend/scripts/seed_data.py b/backend/scripts/seed_data.py
index b200891..dc3c55a 100644
--- a/backend/scripts/seed_data.py
+++ b/backend/scripts/seed_data.py
@@ -121,15 +121,16 @@ def seed(db: Session):
         print("ERROR: No user found in database. Create a user first.")
         return
 
-    # Delete existing portfolio if present (cascade deletes related records)
-    existing = db.query(Portfolio).filter(
+    # Delete all existing portfolios with this name (cascade deletes related records)
+    existing_list = db.query(Portfolio).filter(
         Portfolio.user_id == user.id,
         Portfolio.name == "연금 포트폴리오",
-    ).first()
-    if existing:
+    ).all()
+    for existing in existing_list:
         db.delete(existing)
-        db.flush()
         print(f"Deleted existing portfolio (id={existing.id})")
+    if existing_list:
+        db.flush()
 
     # Create portfolio
     portfolio = Portfolio(