The warning
(WARNING/2) Duplicate explicit target name:foo
occurs when you use the same text for two different links in “Named hyperlink references”:
`Foo <http://example.org>`_
`Foo <http://example.com>`_
To circumvent it, use anonymous hyperlink references with double underscores:
`Foo <http://example.org>`__
`Foo <http://example.com>`__
This works without a warning on docutils 0.8.1.