Suggested resolution:

Change in 6.6 [basic.link] paragraph 11 as follows:

For any two declarations of an entity E:

• If one declares E to be a variable or function, the other shall declare E as one of the same type.
• If one declares E to be an enumerator, the other shall do so.
• If one declares E to be a structured binding, the program is ill-formed.
• ...

Consider:

  struct A {
    int a;
  };
  struct B {
    int b;
  };
  auto&& [x] = A{}; //#1
  auto&& [x] = B{}; //#2

A rule is missing to make such repeated structured binding declarations ill-formed.