I installed the DreamHouse app about 2 days ago. When I tried to complete my Trailheads the next day, the app had disappeared from amongst the others in the App Launcher. I then tried to reinstall the app, but it wouldn't reinstall.  Instead, I received an email stating that "Your request to install package "DreamHouse Summer 2017" was unsuccessful. None of the data or setup information in your salesforce.com organization was affected." I haven't been able to resolve the issue as of yet. The email also displays the error message that is needed to correct the issue, if I am able to get any support. It says that there is a duplicate RelationshipName.  "Please rename existing relationship name."

Is anyone able to assist me?