Can I keep my old TWIC upon receiving my new or replacement TWIC card?

No. The TWIC card is property of the federal government.

During the enrollment process, TWIC applicants are required to acknowledge their understanding that when they receive or pick up a new/replacement TWIC, or when their TWIC card expires, they are responsible for turning in their previous TWIC. On receipt of the new TWIC NexGen card, please send the previous and/or expired TWIC to the TSA address on the back of the card or return the card to an enrollment center.