Currently if you want to copy a dashboard it ends up being a different dashboard and URL. Even if the name is the same. So its possible to have more than one dashboard of the same name. Creating a new updated dashboard of same name breaks any bookmark links.
Change “Copy” to “Copy To New” This creates a new dashboard.
Add to options “Copy To Existing” which opens a drop down of all existing dashboards. This allows you to copy the dashboard into an existing dashboard name and overwrite it not changing the URL and not breaking any previous bookmarks or dashboard links to it.