Only one draft of a new page can be saved at a time. If you leave open a new page without ever saving, a draft is saved of that new page. If you try to add another page in another window/tab or on another computer, the draft of your first page will be lost and you will not be able to recover you work. It is gone for good. Confluence should be able to manage multiple drafts on new pages.

To reproduce the issue:
Add a new page. Don't save it.
Allow a draft to be saved.
Open a new tab/window.
Add a new page.
Ignore the note that asks if you want to resume/discard.
Enter some information and save the page.
Allow your login to timeout OR close the window tab with the ORIGINAL new page.
View your drafts (User Menu -> Drafts)
There is no draft.
Add a new page.
No message is shown to indicate that you have a draft.
The edits made in your original new page are lost.

For users who switch computers or who work on large NEW pages, this behavior leads to loss of work.