Pages deletes previous versions of files

1) I open a new blank document, enter some text and save it in the documents folder as "test01".

2) I add some more text, go to the top of the document window, click the file name field and change the name to "test02". I then save. "Where" still shows "Documents"

I think I should now have 2 files saved in documents, "test01" and "test02". However "test01" has been deleted by the system. It is gone. Why?