If a button was created from a template(by doing Copy Button and then Use Same Button or by selecting Add Button From Library) two buttons can be linked together so that changes to one button affect a second button. To unlink them;
- Right click one of the buttons and select Remove Button From Page from the popup menu.
- Click on Yes if it asks if you want to remove the button from the page.
- Now right click on the same button that was just removed and select Create New Button from the popup menu.
- Now you should be able to edit this button without it affecting any other button.