Unable to rename Screen name

When I click on Rename for my Screen I cant rename the Screen

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Screen1 can not be re-named; the screen must always be Screen1.    If you add other screens, those screens can be given almost any name.  One option you might have is to 'copy' Screen1 to another screen name ...there are examples of copying screens in the forum.

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refer to: How i do to duplicate screens in app inventor 2?