They can actually transplant a single liver to two people by splitting it [1].

> Approximately 1 in 10 donated livers can be divided into two segments or grafts (this is known as split liver). [...] By splitting the liver into two segments, the donated liver can be used to help two people waiting for a liver transplant.

[1] https://www.nhsbt.nhs.uk/organ-transplantation/liver/is-a-li...

Not so sure about that. A liver can take a heck of a beating, but speak to enough (recovering) alcoholics and you'll find plenty that have managed to knacker their livers.