Hi Philipp,
thank you for reaching this out. I can reproduce the issue. It’s a bug in the DMN model module (i.e. the underlying XML model module). The problem is that both elements are registered for the same name and the model API can’t handle this.
The solution is not to delete InputDataReference because it’s part of the specification (see the XSD). Instead, we should fix the model API so that it can handle duplicated names.
Do you want to work on a pull request?
Best regards,
Philipp