I think there is a little confusion on how Templates actually work.
If you created a page that is a template and create a sub page from that template, then the content of the template page will never show again, it will always show the last page that you have created from that template. Really, the concept would be if you made the about us page a template, then you would make the history page, and then you would create a second sub page (similar to the about us page). so your tree would like this:
About us (Template)
- About us (this is the page that will be shown by default)
- history page (this is another sub page)
and then all you have to do is copy the developer notes from the template page, and by default the About us content will show, and then you will have a history link which would be:
?about-us=2
I hope this will help you.