This plugin allows to create a draft copy of a post or page in two ways:
1. In ‘Edit Posts’/’Edit Pages’, you can click on ‘Duplicate’ link;
2. While editing a post/page, you can click on ‘Copy to a new draft’ above “Cancel”/”Move to trash”.
Both these ways lead to the edit page for the new draft and change what you want then click on ‘Publish’.
Requires WordPress Version: 2.7 or higher