It's possible to order up to six different boards on one panel.

alt To order multiple boards as one panel:
  1. Choose File | New to create a separate design for your panel.
  2. Choose Edit | Select | All and then Edit | Delete to delete the default board outline.
  3. Open one of the boards to be added on the panel, choose Edit | Select | All, Edit | Group or make footprint (choose simply to group), Edit | Copy
  4. Switch to the panel design and choose Edit | Paste.
  5. Repeat the above two steps for all the boards.
  6. Switch to the panel design and posotion the boards so there is at least 2 mm space between boards.
  7. Choose Job | Settings | Specifications | Advanced, check "Panelized with tabs", Panel configuration: 1x1