DataPortal Exception in an existing application

[Chicagoan2016]

We are maintaining an older Csla application and we are getting

Csla.DataPortalException: 'DataPortal.Create failed (An item with the same key has already been added.)

What could be the possible reason?
Thanks

[Chicagoan2016]

We just restored older code from source control : )

[rockfordlhotka]

Can we get the stack trace? And the version of CSLA you are using?

[Chicagoan2016]

We had the same exception today, turned out we were calling
InputProperties.Add(...) twice for the same property