[support] duplicating Database problem

[Roger]

Using Drupal 7.12
I'm building a live site and wish to duplicate the database.
I used phpmyadmin to copy the database on the server and cpanel to 
download to my pc.

I keep running into an error:
ERROR 1062 (23000) at line 27: Duplicate entry 'comment_publish_action' 
for key 'PRIMARY'

I have tried mysql -uname -pword database < copied_data.sql copied the 
structure,
have copied the structure only then tried to insert the data but get the 
same error.
I tried deleting the offending INSERT INTO table but the error simply 
transfers to the next INSERT.
Haven't run into this before!
Where should I look for help please.
Thanks
Roger