Have you checked the birth date for the 2 people you've found? It is possible using the free search, albeit a bit tedious. Enter the exact birth year and then work through the months until you get a match, and then do the same for the days.
That said, if he is a bigamist I doubt if he'd have any scruples about fibbing about his birth date.
As for learning things from the register, I've found it quite useful in tracing family members and helping confirm marriages. And the occasional oddity, such as men having their surname amended. I have found quite a few instances of birth dates being slightly off though (eg the day and month correct but the year incorrect), so you have to be bit wary of the dates.