It’s definitely not an urban legend; although male multiple orgasms do sometimes take on something of a mythic quality (take, for example, Sting).
The good news is that men can, do, and have had multiple orgasms for thousands of years. Taoist teachings on sexuality that go back farther than that give explicit instruction for men on how they can experience multiple orgasms. Western sex researchers have also studied this experience in men and found clear physiological evidence that it happens. Also, it seems that many men can learn to have multiple orgasms.
The sort-of bad news? Learning to have multiple orgasms takes a fair bit of time and practice. Also, multiple orgasms means that you are having a series of non-ejaculatory orgasms, so while they aren’t necessarily better or worse, they are definitely different than the kind of orgasms you may be used to experiencing.
The more good news? Learning to have multiple orgasms means you will also be learning to control ejaculation, and you will learn a lot about your own sexual response, which is great news regardless of the final outcome.