In your query, it is not clear why you issue (renew) letters (contracts) each year. If they are your permanent employees and you are providing all benefits to them, then rather than renewing their contract every year, you should issue them a proper Appointment Letter which does not need to be renewed. You can add a notice period clause which will be applicable to both parties.
Now, coming to your point of issuing a Xerox copy to the staff. Legally, you should print two copies of the letter. The original needs to be issued to the individual, and the employee will acknowledge the other copy. The acknowledged copy should be in your records as a token of acceptance.
The points raised by Mr. Dinesh are also considerable, keeping in view the legal aspects. He is of the opinion (maybe) that you are issuing a contract agreement to avoid PF, ESI, PT, and other statutory benefits. Most companies do such things; in order to avoid statutory costs, they issue a Contract Agreement for one year and do not cover the person(s) under statutory obligations. Such things can be notified and objected to not only by the LO but also by the PF-ESI Inspector.
Mr. Dinesh always provides legal, technical, and logical advice to guidance seekers, so please don’t prolong the issue any more.
Hope this will solve your query. Fellow members can correct me if needed.
Regards