Why is this an issue?

Having all branches of a Select Case or If chain with the same implementation indicates a problem.

In the following code:

Dim b As Integer = If(a > 12, 4, 4)  // Noncompliant

If b = 0 Then  // Noncompliant
    DoTheThing()
Else
    DoTheThing()
End If

Select Case i  // Noncompliant
    Case 1
        DoSomething()
    Case 2
        DoSomething()
    Case 3
        DoSomething()
    Case Else
        DoSomething()
End Select

Either there is a copy-paste error that needs fixing or an unnecessary Select Case or If chain that needs removing.

Exceptions

This rule does not apply to If chains without Else, nor to Select Case without a Case Else clause.

If b = 0 Then ' No issue, this could have been done on purpose to make the code more readable
    DoTheThing()
ElseIf
    DoTheThing()
End If