runtime error if you attempt to a duplicate to cfg is not default

mpisppy/utils/config.py

@@ -98,8 +98,7 @@ def add_and_assign(self, name, description, domain, default, value, complain=Tru
  """
  if name in self:
  if complain:
- print(f"Duplicate {name=} will not be added to cfg to assign {value=}")
- # raise RuntimeError(f"Trying to add duplicate {name} to self.")
+ raise RuntimeError(f"Trying to add duplicate {name=} to cfg {value=}")
  else:
  self.add_to_config(name, description, domain, default, argparse=False)
  self[name] = value