Ah, okay. Then it is what I described then. That field is an alias field. It updates the name in several spots that are visible to those both taking and working with S123 items, but it does not change the true name of the item. Whatever you first create/publish an item as is its true name.
I try and lecture people on this for SharePoint items and lists all the time. Give something its long-term permanent name first, then you can give it a human-friendly name. Generally speaking, the only thing in SharePoint most people will notice this though is the URL.