I don’t see any option to add a second glossary grid but I did manage to get some results by using the ‘Nickname’ feature, this is a feature which is part of the Advanced model management toolset, see this link. Note that this is only supported by the Standard edition and up.
This option allows you to translate a model element into different languages and seemingly switch between them. This can easily be ‘abused’ to change your glossary as well:
Here I added myself (‘ShelLuser’); I extracted this name from an actor in a Use Case diagram. Then I added a new nickname which I called “Extra glossary” and then renamed my glossary entry in “Test user”, you can see the results above.
While this is not fully the same as a new Glossary diagram it can mimic that behavior a bit (so I think).
Hope this can help!
There’s another interesting trick which you can use and I think it’s a lot less ‘invasive’ than nick names are: add a new grid (diagram). Preferably in a new model of its own, then be sure to set its scope to your current model only and you’d have what you require:
Here I added a new model called ‘test’ in the project overview (easily seen when using the project explorer, but for demonstration purposes I also opened the model explorer pane) and then added my new grid and set the scope.
The end result is a grid which somewhat behaves as a glossary grid but of course without the same functionality (you can’t add something to this grid in the same way).
Still hope it can help.