If you've manually created a permission set for a page, and you want to apply the same permission set to another page, you can copy the full set to that page.
To access the Page Permissions and the Current Permission Set, see Access Page Permissions.
To copy a full Permission Set, do the following:
Under Permissions, scroll to the bottom of the Current Permission Set grid, and then click Copy.
The permission set remains copied to the clipboard until you log out of your RediSite.
Navigate to the other page's permission set, scroll to the bottom of the Current Permission Set grid, and then click Paste.