If we consider formal integration (OOTB); only one bacuse of sm-rfc-mapping.xml file (in SM) has only field definition. I mean this hasn't got any PPM server definition. You can define more than one server in ppmIntegration table (in SM) but the because of the file, SM can not know where should send data.
But there is always a solution :) Without formal integration I think you can do it with ConnectIT. This tool is a bridge between HP and Non-HP systems and has programmablility capability. Can consume web services vs. For more detail you can get documantion about ConnectIT from HP site.
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IT Governance Professional & PPM Solution Architect