More fixes

phiml/math/_nd.py

@@ -52,7 +52,9 @@ def vec(name: Union[str, Shape] = 'vector', *sequence, tuple_dim=spatial('sequen
         assert not components, "vec() must be given either positional or keyword arguments but not both"
         if len(sequence) == 1 and isinstance(sequence[0], (tuple, list)):
             sequence = sequence[0]
-        dim = dim.with_size([str(v) for v in sequence])
+        item_names = [str(v) for v in sequence]
+        if len(set(item_names)) == len(item_names):
+            dim = dim.with_size(item_names)
         return wrap(sequence, dim)
     else:
         def wrap_sequence(value):

phiml/math/_trace.py

@@ -881,7 +881,7 @@ def to_sparse_tracer(tracer: Tensor, ref: Optional[Tensor]) -> SparseLinTracer:
     if isinstance(tracer, ShiftLinTracer):
         matrix, bias = tracer_to_coo(tracer, sparsify_batch=False, separate_independent=False)
         src_dims = dual(matrix) - set(tracer._renamed)
-        matrix = rename_dims(matrix, src_dims, [n + '_src' for n in src_dims.as_batch().names])
+        matrix = rename_dims(matrix, src_dims, [f'~{n}_src' for n in src_dims.as_batch().names])
         return SparseLinTracer(tracer._source, matrix, bias, tracer.shape)
     assert isinstance(tracer, GatherLinTracer)
     if tracer._selection is None: