check for doubles

uploader.py

@@ -198,15 +198,16 @@ def delete_book(cfg: CalibreConfig, book_id: int) -> tuple[bool, str]:
 
 
 def find_duplicate_groups(books: list[dict]) -> list[list[dict]]:
-    """Group books by normalised title; return only groups with 2+ entries."""
+    """Group books by normalised title+author; return only groups with 2+ entries."""
     from collections import defaultdict
     groups: dict[str, list[dict]] = defaultdict(list)
     for book in books:
-        title = book.get("title", "")
-        # Normalise: lowercase, strip punctuation and extra whitespace — no word removal
-        key = re.sub(r"[^\w\s]", " ", title.lower())
-        key = re.sub(r"\s+", " ", key).strip()
-        if key:
+        title = re.sub(r"[^\w\s]", " ", book.get("title", "").lower())
+        title = re.sub(r"\s+", " ", title).strip()
+        authors = re.sub(r"[^\w\s]", " ", book.get("authors", "").lower())
+        authors = re.sub(r"\s+", " ", authors).strip()
+        key = f"{title}||{authors}"
+        if title:
             groups[key].append(book)
     return sorted(
         [g for g in groups.values() if len(g) > 1],