Fixing ORABPEL-02117 Variable already declared. A variable with key "XXXX" is already declared in the current scope.

A surprise error message occurs after the successful deploy of the BPM project. To resolve it look for duplicate definitions in the BPMN process files. In my case I had:

<ns5:Conversation id="CONVERSATION155142191537" type="service_call">
          <ns5:ServiceCallConversationDefinition service="Services.Externals.GetApplicationData"/>
         </ns5:Conversation>
         <ns5:Conversation id="CONVERSATION176785361049" type="service_call">
          <ns5:ServiceCallConversationDefinition service="Services.Externals.GetApplicationData"/>
         </ns5:Conversation>

Removed the first occurrence and updated Conversation id to the value of the second occurrence and redeployed. The error has been resolved!