diff --git a/manim/utils/iterables.py b/manim/utils/iterables.py
index 196248cd73..cdd41e59d0 100644
--- a/manim/utils/iterables.py
+++ b/manim/utils/iterables.py
@@ -143,6 +143,7 @@ def list_difference_update(l1: Iterable[T], l2: Iterable[T]) -> list[T]:
         >>> list_difference_update([1, 2, 3, 4], [2, 4])
         [1, 3]
     """
+    l2 = set(l2)
     return [e for e in l1 if e not in l2]
 
 
@@ -158,7 +159,8 @@ def list_update(l1: Iterable[T], l2: Iterable[T]) -> list[T]:
         >>> list_update([1, 2, 3], [2, 4, 4])
         [1, 3, 2, 4, 4]
     """
-    return [e for e in l1 if e not in l2] + list(l2)
+    l2 = list(l2)
+    return list_difference_update(l1, l2) + l2
 
 
 @overload
diff --git a/tests/module/utils/test_iterables.py b/tests/module/utils/test_iterables.py
new file mode 100644
index 0000000000..6f52d7441b
--- /dev/null
+++ b/tests/module/utils/test_iterables.py
@@ -0,0 +1,35 @@
+import pytest
+
+from manim.utils.iterables import list_difference_update, list_update
+
+
+def test_list_difference_update_removes_matching_items():
+    assert list_difference_update([1, 2, 3, 4], [2, 4]) == [1, 3]
+
+
+def test_list_difference_update_preserves_duplicates_and_order():
+    assert list_difference_update([3, 1, 3, 2, 1], [1]) == [3, 3, 2]
+
+
+@pytest.mark.parametrize(
+    ("l1", "l2", "expected"),
+    [([1, 2, 3, 4], [2, 4], [1, 3]), ([], [1, 2], [])],
+)
+def test_list_difference_update_removes_elements(l1, l2, expected):
+    assert list_difference_update(l1, l2) == expected
+
+
+def test_list_difference_update_preserves_l1_order_and_duplicates():
+    assert list_difference_update([3, 1, 3, 2, 1], [1]) == [3, 3, 2]
+
+
+@pytest.mark.parametrize(
+    ("l1", "l2", "expected"),
+    [([1, 2, 3], [2, 4], [1, 3, 2, 4]), ([], [1, 2], [1, 2])],
+)
+def test_list_update_removes_overlap_and_appends_l2(l1, l2, expected):
+    assert list_update(l1, l2) == expected
+
+
+def test_list_update_preserves_duplicates_in_l2():
+    assert list_update([1, 2, 3], [2, 4, 4]) == [1, 3, 2, 4, 4]