When you copy a page that has a configured DUD module on it and specify 'copy' for the DUD module. The module on the new page will display correctly until you update any of the templates. After which the module will throw an error.
This appears to be due to the fact that the 'list' template definition when copied includes serverside code.
Using DNN 4.9.4 & DUD 2.5.5
Edit: The same appears to happen if you 'export content' (ie the module settings) from one module and import it to another