No. There is a content lock module in place that prevents that. Users should expect to get a box at the top of a page they’re editing telling them that the page they’ve entered is now locked. The lock will time out in 1 hour’s time:

content lock message

If you navigate away from the page you have open without saving thereby releasing the lock, you will get a message reminding you that the page is locked for others upon going into another page:

content lock by you message


What happens to my content when the page lock expires?

If you have not saved the draft, then when your page lock expires, your unsaved changes will be lost.