Could be just HR exercise.
Could be somebody lost some forms.
No reason to do them now if you completed one at the time of hire.
According to the form, the I-9 is done at the time of hire and there is no requirement to re verify except on employees who hold a green-card.
Some employers have been known to use the I-9 as a means of discriminating or obtaining information that they are not allowed to ask due to privacy laws in some states.
According to the form instructions, "Employers CANNOT specify which document(s) they will accept from an employee." Review the
I-9 form and decide what ID you would like to bring in. Don't let them decide for you.
Also, if your company is a Federal Contractor, as of Sep 2009 they were supposed to be running everyone's info through
E-Verify.