Why is this an issue?
It is highly suspicious when a value is saved for a key or index and then unconditionally overwritten. Such replacements are likely errors.
Noncompliant code example
list[index] = "value 1";
list[index] = "value 2"; // Noncompliant
dictionary.Add(key, "value 1");
dictionary[key] = "value 2"; // Noncompliant
