I removed all extension on chrome.
Whereupon , there has not occurred DOM Exception during page load in chrome console.
But still continues the duplicate user.
If only occurs this error me , then may be due to my local configuration.
Thanks for the extra information. It turns out the JS errors had nothing to do with the issue.
The problem is that in order to get the back and forward buttons to work without refreshing the page, we cache the html. However our JS doesn't take this into account and that is why you are getting the duplication. I've added this bug to our backlog, please watch this issue for further updates.
In the meantime, you can fix this problem by clicking on the 'Access management' link, or refreshing the page.