Beth,
OK- I logged in and took a look at your functions.php. The code in your functions.php is fine.
BUT you are also using the plugin BP WC Vendors. The same function(must be declared differently) is in that plugin- so now you are seeing it twice.
So, either remove the code form us, or remove the BP WC Vendors plugin.
You can also talk to the author of the BP WC Vendors plugin, he is typically quite helpful. He could help you write a functions in your functions.php to change the button for your shop header if needed; direct him to this thread and the conversation we had above so he can see your dilemma with the button.
