Hi HomerJ,
I am understanding that when you are creating a new project, the dropdown box for selecting the DB has both the old and new DB servers showing within it. This is is correct functionality as that box is populated from the list of all DBs listed under the DB server's tab (if you had more DB server's listed there they too would show in that drop down box as well) of the Site Admin section.
In order to not have DB servers show in that drop down box, you will have to remove all undesired DB servers from the DB server tab. As long as there are no projects associated with that DB you can remove it from the DB Server tab and it will not show there anymore. That is the only way to suppress the excess DB servers from appearing in the new project drop down box.
Hope this helps,
Dan