I'm kicking myself for upgrading tonight. The new 2019.3.2 version seems to filter duplicate filenames in the tab switcher, which makes no sense. If you have the same file open in two tabs, you've by definition split the window. You should be able to (and until now, always have been able to) use the switcher keyboard shortcut to switch between the two tabs that show the same file. I often use this to view one part of a long file while working on another part.
But since the upgrade, the switcher only lists the most recently visited tab for a file that's open in multiple tabs. So if you split the editor window and then open the same file on either side of the split, there's no keyboard shortcut to switch the focus between them. Someone clearly thought showing the same filename twice in the switcher was a bug, but it's not.