Hi Michael,
This is a new feature in Encore 2 called, “Sync Button Text and Name”. It is very helpful if you design or edit your menus inside of Encore, but, as you have discovered, it is deadly when you take your pre-designed buttons and link them to program content.
The best way to handle this is to use the Menus panel (not the viewer) and select all of the buttons in a menu all at once, then use the Properties panel to de-select the SBTAN checkbox. Repeat for each menu in your project. Accomplish this task BEFORE you start linking the buttons.
AFAIK, several thousand feature requests to have a Preference for SBTAN to be on or off by default have already been filed, but it wouldn’t hurt for you to go to the Adobe site and file one too.
-Jeff