[GENERAL] SELECT duplicates in a table

[Kall, Bruce A.]

I've look for a solution to this, but have only been able to find 
solutions to delete duplicate entries in a table by deleting entries not 
returned by SELECT DISTINCT.

What sql should I use to SELECT entries in a table that have two 
particular column values that match?

For example, my_table has
name, phone number, identification_number, zip code, date of birth, and city
I want to SELECT rows from this table that have the same values in 
identification and date of birth (duplicates) so I can have the user 
look at them in order to figure out which one to delete.

I tried something like:
 $db_sql = "SELECT * FROM my_table GROUP BY identification_number 
HAVING count(date_of_birth) > 1 ORDER BY name"

but that doesn't seem to work.
Thanks,
Bruce
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