Why is this an issue?
Storing a value inside a collection at a given key or index and then unconditionally overwriting it without reading the initial value is a case of a "dead store".
towns.Item(x) = "London"
towns.Item(x) = "Chicago"; // Noncompliant
This practice is redundant and will cause confusion for the reader. More importantly, it is often an error and not what the developer intended to do.