This should not be a common issue where the page name is changed and then changed back without saving. In any case it can be worked around easily by manually changing the url back as you would like it to be or just cancel without doing any saving.
When you rename it and a new url is suggested and then you save, what happens is that a permanent redirect is created from the old url to the new url, and then the old url cannot be used again, you can find these under Administration > Advanced Tools > 301 Redirect Manager
So in this case if you have saved it then you try to rename it back to the original page name and url, it will not allow you to use the url again because this would create an infinite redirect loop in the browser. So you must first go and manually delete the 301 redirect before you can use the url again.
The issue is that we are not currently passing a page id to the url suggest service and since it won't suggest an existing url it does not restore the current page url in this scenario when you rename it and then rename it back without saving. It can be fixed probably by changing the logic to pass in the current page guid and allow suggesting the current url as long as it is the same page. I have made a note of it and will get to it when I have a chance.