To reproduce using the Monkey Tester:

- open the menu bar page
- turn on the Voice Over
- click on a menu in the inner MenuBar, down arrow until the last submenu
- press SPACE to open the submenu
the VO announces "you are on blah blah, to select this menu press control-option-space"
- press control-option-space

What I see is that somehow both the main menu and the inner menu bar are activated. LEFT/RIGHT arrow keys result in both menu bars selection changing, etc. This does not happen in the master branch (it does not seem to mention the control-option-space). See the attached screenshot.