Find double (not uniqe) entries in a table

[security.member]

Hi,

I've got a table that looks like this (offcourse, the real one is much bigger):

id| name | city
1 | john | 19
2 | bella | 11
3 | john | 12
4 | mike | 06
5 | alex | 12
6 | simon | 19
7 | alex | 11

.. and I want to select the 'id', 'name' and 'city' of those entries that the field
'name' isn't uniqe, in this case, john and alex.

How should my sql-query look like?

Thanks,
--Alexander.