Some panel layouts (Cupertino and Contemporary) and the general use of the Global Application Menu result in duplication menus displaying, one set in the application and one set in the Global Application Menu. See the attached screenshots.
Let me know if I can provide any other information about this issue.
Here is another screen shot from the Ubuntu Mate forums showing the same issue plus the file menu items repeating horizontally to the right across the top panel.
Ubuntu Mate 20.04 beta
Some panel layouts (Cupertino and Contemporary) and the general use of the Global Application Menu result in duplication menus displaying, one set in the application and one set in the Global Application Menu. See the attached screenshots.
Let me know if I can provide any other information about this issue.