I9 form is a US federal government requirement based on the Immigration Reform and Control Act passed in 1986.
If you were hired before that date and stayed with your employer; the employer was exempt from having this on file. The auditor would see your hire date was previous to law being passed.
If you were hired by an employer after 11/6/1986 you must fill out I9 and the employer must have it on file if audited. Those that were hired at Xerox or subsidiary prior to 1986 did not have to fill this form out. If you left Xerox employment and are re-hired you need to fill this out because your hire date is now after 1986.
If Xerox HR had a completed I9 on file; they may have provided it to HCL.
If Xerox did not have I9 on file (or lost it); then you will need to complete one for HCL. There are 2 steps to the form. One you fill out; the 2nd is completed by the employer. To ensure the employer section is filled out properly and the proper verification documents are used; employers typically have a HR trained person doing the processing. So your being asked to go off site may be to meet with this trained person.