Depends how you want to setup Telegram on the second phone, a separate/dedicated Telegram account (for use by another individual) or a shared Telegram account for both phones (only used by you).
If you use a separate Telegram account, for example, you can add a second Telegram configuration node in Node-RED.
As far as I known you also can add the second user ID in the existing Telegram bot configuration node.
Documentation:
Also beware, as far I understand, using Telegram in HA (by configuration made in configuration.yaml) is separated from the Node-RED configuration, so don’t mix that up.
Documentation:
I didn’t tried this myself, I have an other setup (dedicated Node-RED config on a dedicated Node-RED server) so maybe someone else could chime in.
EDIT: Also you can check @gerard33 solution if it is suitable for you:
and/or