Your friend needs to write a reply stating the fact that CIC has clear instructions on the required content of such employment letters (tenure, designation, work hours, salary, and main duties).
So when he requested his employers for a letter, they asked if there is any format can be provided. So he provided them with a format.
But, firmly state that the the content of each letter is genuine, and if possible, get fresh letters from all the employers again. This time, present the same content in different formats. Try using different synonyms and phrases.
Then, attach visiting cards of employers and indicate the visa officer that he can verify with the employers.
Moreover, try to attach proofs of his employments. The following list should be helpful
Copies of:
#appointment letter
#promotion/increment letter
#final settlement letter (for past employers)
#email/written communication between him and his colleagues
#certificates of training, awards etc.
#payslips (get them attested from employer)
#tax deposit slips in his name
#your visiting cards
#pictures of him and his colleagues
#Linkedin recommendations from current/ex colleagues
Please remember that success rate after getting Procedural Fairness is not hopeful at all. So tell your friend to do his best and pray to God.
Thanks
Desertfox