diff --git a/src/bot/plugins/builtin/spam.py b/src/bot/plugins/builtin/spam.py
index ce94bc1..0a34d7a 100644
--- a/src/bot/plugins/builtin/spam.py
+++ b/src/bot/plugins/builtin/spam.py
@@ -44,11 +44,14 @@ def register_inline_keyboard_spam(application: Application) -> list[BaseHandler]
 def register_bio_bait_spam(application: Application) -> list[BaseHandler]:  # type: ignore[type-arg]
     """Register bio bait spam handler (group=4).
 
-    Callback wrapped with ``guard_plugin("bio_bait_spam")``.
+    Callback wrapped with ``guard_plugin("bio_bait_spam")``. Shares group=4
+    and filter shape with ``duplicate_spam``; ``block=False`` so both get a
+    chance to run instead of the first match swallowing the update.
     """
     handler: BaseHandler = MessageHandler(
         BIO_BAIT_FILTER,
         guard_plugin("bio_bait_spam")(handle_bio_bait_spam),
+        block=False,
     )
     application.add_handler(handler, group=4)
     logger.info("Registered handler: bio_bait_spam_handler (group=4)")
@@ -83,11 +86,15 @@ def register_new_user_spam(application: Application) -> list[BaseHandler]:  # ty
 def register_duplicate_spam(application: Application) -> list[BaseHandler]:  # type: ignore[type-arg]
     """Register duplicate message spam handler (group=4).
 
-    Callback wrapped with ``guard_plugin("duplicate_spam")``.
+    Callback wrapped with ``guard_plugin("duplicate_spam")``. Registered
+    before ``bio_bait_spam`` in the same group with the same filter shape;
+    ``block=False`` so PTB still checks the next handler in group=4 instead
+    of stopping after this one matches.
     """
     handler: BaseHandler = MessageHandler(
         filters.ChatType.GROUPS & ~filters.COMMAND,
         guard_plugin("duplicate_spam")(handle_duplicate_spam),
+        block=False,
     )
     application.add_handler(handler, group=4)
     logger.info("Registered handler: duplicate_spam_handler (group=4)")
diff --git a/tests/test_main_plugins_bootstrap.py b/tests/test_main_plugins_bootstrap.py
index 2fb72c0..bd85cfb 100644
--- a/tests/test_main_plugins_bootstrap.py
+++ b/tests/test_main_plugins_bootstrap.py
@@ -321,6 +321,27 @@ def test_spam_has_duplicate_spam_registrar(self):
         assert hasattr(spam, "register_duplicate_spam")
         assert callable(spam.register_duplicate_spam)
 
+    def test_duplicate_spam_and_bio_bait_spam_share_group_and_filter_shape(self):
+        """duplicate_spam and bio_bait_spam sit in group=4 with the same filter shape.
+
+        Regression guard for the collision this test class is named after: both
+        handlers match on ChatType.GROUPS & ~COMMAND. If either loses its
+        ``block=False``, PTB's default first-match-wins behavior within a group
+        makes whichever registers first (duplicate_spam, per MANIFEST_ORDER)
+        permanently swallow every update in group=4, and the other handler's
+        callback is never invoked.
+        """
+        from bot.plugins.builtin import spam
+
+        app = MagicMock()
+        app.add_handler = MagicMock()
+
+        dup_handlers = spam.register_duplicate_spam(app)
+        bait_handlers = spam.register_bio_bait_spam(app)
+
+        assert dup_handlers[0].block is False
+        assert bait_handlers[0].block is False
+
     def test_captcha_has_registrar(self):
         """bot.plugins.builtin.captcha has register_captcha function."""
         from bot.plugins.builtin import captcha as captcha_mod