MySQL Issus: copy from tables

[FatalBreeze]

I dont need to use the impex.
I dont really care about those 40,000 users, only for their email address and the forum stats, not about their posts and etc.

I can use the query INSERT ... SELECT, but i don't know how to use the ON DUPLICATE KEY, i want it to do nothing if the key already exists.

Can you please add more light on this query?

Is it possible that the query should be:

INSERT IGNORE INTO `user` (userid, username, ...)
SELECT * FROM `user_backup`;