diff --git a/tests/test_mapper_no_duplicate_keys.py b/tests/test_mapper_no_duplicate_keys.py
new file mode 100644
index 0000000000..42e49415fd
--- /dev/null
+++ b/tests/test_mapper_no_duplicate_keys.py
@@ -0,0 +1,53 @@
+# SPDX-License-Identifier: AGPL-3.0-only
+# Copyright 2026-present the Unsloth AI Inc. team. All rights reserved.
+
+"""Guard against duplicate keys in the ``__INT_TO_FLOAT_MAPPER`` registry.
+
+Duplicate keys in the dict literal silently overwrite earlier entries.
+We inspect the source with ``ast`` to ensure there are no duplicates.
+"""
+
+import ast
+import os
+
+MAPPER_PATH = os.path.join(os.path.dirname(__file__), os.pardir, "unsloth", "models", "mapper.py")
+
+
+def _duplicate_int_to_float_keys():
+    with open(MAPPER_PATH, encoding = "utf-8") as f:
+        tree = ast.parse(f.read(), MAPPER_PATH)
+
+    for node in ast.walk(tree):
+        if not isinstance(node, ast.Assign):
+            continue
+        for target in node.targets:
+            # Private names are mangled at code generation, which ``ast.parse``
+            # never reaches, so the identifier reads exactly as written.
+            if isinstance(target, ast.Name) and target.id == "__INT_TO_FLOAT_MAPPER":
+                if not isinstance(node.value, ast.Dict):
+                    continue
+                # mapper.py reads the nested per-precision dicts directly, so
+                # check every dict. Count per dict: "16" and "8" legitimately
+                # repeat across sibling entries.
+                duplicates = {}
+                for mapping in ast.walk(node.value):
+                    if not isinstance(mapping, ast.Dict):
+                        continue
+                    seen = set()
+                    for k in mapping.keys:
+                        if not (isinstance(k, ast.Constant) and isinstance(k.value, str)):
+                            continue
+                        if k.value in seen:
+                            duplicates.setdefault(k.value, []).append(k.lineno)
+                        seen.add(k.value)
+                return duplicates
+    raise AssertionError("Could not find the __INT_TO_FLOAT_MAPPER dict literal in mapper.py")
+
+
+def test_int_to_float_mapper_has_no_duplicate_keys():
+    duplicates = _duplicate_int_to_float_keys()
+    assert not duplicates, (
+        "Duplicate keys in __INT_TO_FLOAT_MAPPER silently overwrite earlier "
+        "entries and corrupt model resolution. Remove the redundant "
+        f"literal(s), key -> line number(s) in mapper.py: {duplicates}"
+    )
diff --git a/unsloth/models/mapper.py b/unsloth/models/mapper.py
index 4558bb0f28..747b3bb986 100644
--- a/unsloth/models/mapper.py
+++ b/unsloth/models/mapper.py
@@ -94,10 +94,6 @@ __INT_TO_FLOAT_MAPPER = \
         "unsloth/llama-2-7b-chat",
         "meta-llama/Llama-2-7b-chat-hf",
     ),
-    "unsloth/llama-2-7b-chat-bnb-4bit" : (
-        "unsloth/llama-2-7b-chat",
-        "meta-llama/Llama-2-7b-chat-hf",
-    ),
     "unsloth/Mixtral-8x7B-v0.1-unsloth-bnb-4bit" : (
         "unsloth/Mixtral-8x7B-v0.1",
         "mistralai/Mixtral-8x7B-v0.1",