As xmls are read top down, if you have items named the same that come later, it will just replace what was before. You'd need to rename them to something different for them to be separate item modifiers than the vanilla ones. Otherwise, when the xml is read, since your names are exactly the same, it will just keep whichever was read last (since you're using append, it will always be yours as append puts code at the end of the xml, just before the last closing tag)
Also, just to help you when you run into errors later, I see you have spaces in your weapon names. You'll one day encounter some issues if you do that. Some xmls do weird things when there is a space in an item name. You can use localization to add spaces and hyphens and what not. Just a tip for ya