The entire document should be one side only and the Annexure is also supposed to be on the Company letter head. Ensure that every page is initialed with company seal and final page with full signature as this is the agreement between the employee & employer. In case of any dispute this is the document going to be the base document, this document reflects the image / standard of the organization hence avoid printing on the back side, use separate paper & ensure the matter is being printed on one side only.
Thanks
Kamesh