It is highly suspicious when a value is saved for a key or index and then unconditionally overwritten. Such replacements are likely in error.
fruits[1] = 'banana';
fruits[1] = 'apple'; // Noncompliant - value on index 1 is overwritten
myMap.set('key', 1);
myMap.set('key', 2); // Noncompliant - value for key "key" is replaced
mySet.add(1);
mySet.add(1); // Noncompliant - element is already in the set