[INVESTIGATING] Board Doubling on dashboard

Hello! I'm an English teacher and have been using your board for some time. The problem is that yesterday I decided to share the link to my board to all my students, giving them access only to view the board. Having used the link myself, I found myself on Miro, yet it'd been doubled this time. Now the other board appears every now and then, yet while entering Miro it isn't there for some time until I open my board. (video 1) I now have two seemingly identical boards and can't modify one. If I decide to change anything in one, the other automatically changes the very same thing. (video 2) Please what should I do to solve an issue? How can I get rid of the unnecessary board? And does deleting the one which I don't need entail automatic deletion of the other?