> The best strategy is fixing your data-model so that you have a unique key. As you found out already, e-mail addresses aren't very suitable as unique keys for people. For this particular case I'd suggest adding a surrogate key.
>
> Alternatively, you might try using (first_name, email) as your key. You'll probably still get some duplicates, but they should be less and perhaps few enough for your case.
>
Yea I'll have to see if I can do a better match.