I guess it depends on how much freedom an HM has. Where I've worked, the answer has been "more than enough". Which means you can easily ask e.g. a philosophical question. Ask something unrelated to the job, see what kind of person they are. Chance they'll both respond the exact same way is negligible, and you'll very likely come out preferring one of them. Only few people lie when you give them a good question that doesn't sound like it has a "wrong" answer that would get them a minus.

Does this mean you'll necessarily get the best candidate? No, but it's better than selecting on a proxy for willingness to lie, that's how you end up with people far too good at political games, to detriment of the org.

In places where the HM has little freedom, I guess there's little choice indeed. But even then, I'd try to go with whorver sounds most happen and genuine, rather than most interested in the company per se.