Bug "Item with the same key has already been added" when using index operator to replace a local variabl

When using the indexing operator on a `LocalizedString` to set a new value for a local variable, I'd expect it to behave the same as a `Dictionary<T>` instead of throwing an ArgumentException.

Eg.

Code (CSharp):

1. // If "VariableName" already existed, it should be replaced silently
2. _locString["VariableName"] = someOtherLocString;
3.  
4. // But this should throw, this `Dictionary<T>`'s .Add() API only allows adding new keys
5. _locString.Add("VariableName", someOtherLocString);
6.  

For now I'm just removing the key before re-adding to change its value, eg.

Code (CSharp):

1. _locStringEvent.StringReference.Remove("VariableName");
2. _locStringEvent.StringReference["VariableName"] = newValue;

 

Great, thanks!