Do not fail if we try to add the same remote twice. (fix #357)
If we try to add a remote already existing (same id) with same url, print a warning.
If we try to add a remote already exsting but with different url, raise as usual.
If we try to add a remote already existing (same id) with same url, print a warning.
If we try to add a remote already exsting but with different url, raise as usual.