Import db without violating unique constraints

[Pooja Gupta]

I create a dbdump using a cron job that runs everyday :
mysqldump -u user -ppass --opt --complete-insert --triggers --single-transaction <dbname>> dbv1_%date:~7,2%-

I now want create another cron job on another db that keeps the backup (I have to make this other db the master for the third db, thus cannot use automatic replication here). But since there are unique contraints on most of the tables, the import fails saying that the constraints are getting violated.

How should I import the db in append only mode ?