If I understand correctly, you have a Proxy based on this WSDL, and in this proxy you have two operations op1 and op2, and they have the same input parameters. Let's call this proxy "ClientProxy"
Let's start with an empty implementation of op2, that is, the request and response pipelines would be empty.
Now add a add a Service Callout action on op2. It can be in the request or response pipeline. This Service Callout has properties service = ClientProxy, invoking = op1
When you call op2 from a client or tester, you would pass the input parameters. The Service Callout action will take this parameters and send them to the op1, and put the response back in the $body