I have found a fairly simple work around to this issue that doesn’t require very heavy php so I thought I would share. However it can only be done with the calendar widget and not the full feature calendar, but it ended up being an acceptable solution for us.
First create a page template for your custom page that calls a page sidebar. Then using the “display widgets” plugin, you can easily create multiple calendar widgets and control which pages they are displayed on.
I hope this method ends up being a suitable work around for some people.