Merging Clients/Projects

I have had a few instances when I send a contract over to a client, the client will sign the contract but then request a new project from me. Then I end up with 2 projects for one client. Is there a way to merge projects when this happens? Or possibly have a toggle to turn off the request a new project? This is extremely frustrating because I end up with one project with the contract and the other with a filled out questionnaire and asking for the project that I have already started.