This Convention shall not abrogate multilateral or bilateral copyright
conventions or arrangements that are or may be in effect exclusively
between two or more American Republics. In the event of any difference
either between the provisions of such existing conventions or
arrangements and the provisions of this Convention, or between the
provisions of this Convention and those of any new convention or
arrangement which may be formulated between two or more American
Republics after this Convention comes into force, the convention or
arrangement most recently formulated shall prevail between the parties
thereto. Rights in works acquired in any Contracting State under
existing conventions or arrangements before the date this Convention
comes into force in such State shall not be affected.