Uh, don't do that if you expect your mail to be delivered.
Multiple PTRs, depending on how the DNS service is set up, may be returned in round-robin fashion, and if you return a PTR that doesn't match what your HELO claims you are, then congrats on your mail being likely tossed in the trash.
Pick the most accurate name (that is, match your HELO domain), and only set one PTR.
(Useless fact of the day: multiple A records behave the same way and you can use that as a poverty-spec version of a load balancer.)
Yeah, I noticed that.
It's on my to-do list for next week since I should have time to sort that out/file a bug if it's something that's not a configuration error.