diff --git a/masque/library.py b/masque/library.py
index bb2e3d2..13b4d26 100644
--- a/masque/library.py
+++ b/masque/library.py
@@ -1037,6 +1037,18 @@ class ILibrary(ILibraryView, MutableMapping[str, 'Pattern'], metaclass=ABCMeta):
             def label2name(label: tuple) -> str:        # noqa: ARG001
                 return self.get_name(SINGLE_USE_PREFIX + 'shape')
 
+        used_names = set(self.keys())
+
+        def reserve_target_name(label: tuple) -> str:
+            base_name = label2name(label)
+            name = base_name
+            ii = sum(1 for nn in used_names if nn.startswith(base_name)) if base_name in used_names else 0
+            while name in used_names or name == '':
+                name = base_name + b64suffix(ii)
+                ii += 1
+            used_names.add(name)
+            return name
+
         shape_counts: MutableMapping[tuple, int] = defaultdict(int)
         shape_funcs = {}
 
@@ -1053,6 +1065,7 @@ class ILibrary(ILibraryView, MutableMapping[str, 'Pattern'], metaclass=ABCMeta):
                         shape_counts[label] += 1
 
         shape_pats = {}
+        target_names = {}
         for label, count in shape_counts.items():
             if count < threshold:
                 continue
@@ -1061,6 +1074,7 @@ class ILibrary(ILibraryView, MutableMapping[str, 'Pattern'], metaclass=ABCMeta):
             shape_pat = Pattern()
             shape_pat.shapes[label[-1]] += [shape_func()]
             shape_pats[label] = shape_pat
+            target_names[label] = reserve_target_name(label)
 
         # ## Second pass ##
         for pat in tuple(self.values()):
@@ -1085,10 +1099,10 @@ class ILibrary(ILibraryView, MutableMapping[str, 'Pattern'], metaclass=ABCMeta):
             #  For repeated shapes, create a `Pattern` holding a normalized shape object,
             # and add `pat.refs` entries for each occurrence in pat. Also, note down that
             # we should delete the `pat.shapes` entries for which we made `Ref`s.
-            shapes_to_remove = []
             for label, shape_entries in shape_table.items():
                 layer = label[-1]
-                target = label2name(label)
+                target = target_names[label]
+                shapes_to_remove = []
                 for ii, values in shape_entries:
                     offset, scale, rotation, mirror_x = values
                     pat.ref(target=target, offset=offset, scale=scale,
@@ -1100,7 +1114,7 @@ class ILibrary(ILibraryView, MutableMapping[str, 'Pattern'], metaclass=ABCMeta):
                     del pat.shapes[layer][ii]
 
         for ll, pp in shape_pats.items():
-            self[label2name(ll)] = pp
+            self[target_names[ll]] = pp
 
         return self
 
diff --git a/masque/test/test_library.py b/masque/test/test_library.py
index e58bd10..335b6ec 100644
--- a/masque/test/test_library.py
+++ b/masque/test/test_library.py
@@ -259,3 +259,43 @@ def test_library_dedup_shapes_does_not_merge_custom_capped_paths() -> None:
 
     assert not lib["top"].refs
     assert len(lib["top"].shapes[(1, 0)]) == 2
+
+
+def test_library_dedup_handles_multiple_duplicate_groups() -> None:
+    from ..shapes import Circle
+
+    lib = Library()
+    pat = Pattern()
+    pat.shapes[(1, 0)] += [Circle(radius=1, offset=(0, 0)), Circle(radius=1, offset=(10, 0))]
+    pat.shapes[(2, 0)] += [Path(vertices=[[0, 0], [5, 0]], width=2), Path(vertices=[[10, 0], [15, 0]], width=2)]
+    lib["top"] = pat
+
+    lib.dedup(exclude_types=(), norm_value=1, threshold=2)
+
+    assert len(lib["top"].refs) == 2
+    assert all(len(refs) == 2 for refs in lib["top"].refs.values())
+    assert len(lib["top"].shapes[(1, 0)]) == 0
+    assert len(lib["top"].shapes[(2, 0)]) == 0
+
+
+def test_library_dedup_uses_stable_target_names_per_label() -> None:
+    from ..shapes import Circle
+
+    lib = Library()
+
+    p1 = Pattern()
+    p1.shapes[(1, 0)] += [Circle(radius=1, offset=(0, 0)), Circle(radius=1, offset=(10, 0))]
+    lib["p1"] = p1
+
+    p2 = Pattern()
+    p2.shapes[(2, 0)] += [Path(vertices=[[0, 0], [5, 0]], width=2), Path(vertices=[[10, 0], [15, 0]], width=2)]
+    lib["p2"] = p2
+
+    lib.dedup(exclude_types=(), norm_value=1, threshold=2)
+
+    circle_target = next(iter(lib["p1"].refs))
+    path_target = next(iter(lib["p2"].refs))
+
+    assert circle_target != path_target
+    assert all(isinstance(shape, Circle) for shapes in lib[circle_target].shapes.values() for shape in shapes)
+    assert all(isinstance(shape, Path) for shapes in lib[path_target].shapes.values() for shape in shapes)