A chain of if/else if statements is evaluated from top to bottom. At most, only one branch will be executed: the first one with a condition that evaluates to true.

Therefore, duplicating a condition automatically leads to dead code. Usually, this is due to a copy/paste error. At best, it's simply dead code and at worst, it's a bug that is likely to induce further bugs as the code is maintained, and obviously it could lead to unexpected behavior.

Noncompliant Code Example

func example(condition1, condition2 bool) {
  if condition1 {
  } else if condition1 { // Noncompliant
  }
}
func SwitchWithMultipleConditions(param int) {
  switch param {
  case 1, 2, 3:
    fmt.Println(">1")
  case 3, 4, 5: // Noncompliant; 3 is duplicated
    fmt.Println("<1")
  }
}

Compliant Solution

func example(condition1, condition2 bool) {
  if condition1 {
  } else if condition2 { // Compliant
  }
}
func SwitchWithMultipleConditions(param int) {
  switch param {
  case 1, 2, 3:
    fmt.Println(">1")
  case 4, 5: // Compliant
    fmt.Println("<1")
  }
}

See