Session tickets are used for TLS session resumption. Usage of multiple tickets is best described in https://www.rfc-editor.org/rfc/rfc9149.html: "For example, clients can open parallel TLS connections to the same server for HTTP, or they can race TLS connections across different network interfaces. The latter is especially useful in transport systems that implement Happy Eyeballs."

In case of web browsers client may connect to the server, download the main page, then get two tickets and open two more connections to fetch resources, immediately using both tickets.

Regarding session resumption, I have only ever seen clients use the second ticket that was issued, never the first.

All the clients I have seen use session tickets in LIFO order. If they receive two tickets, they first use the second ticket, but then the first if they need to establish another connection.