Unable to restore database

I had a site up and running but my hosting company went out of business! I have a database backup and thought I could restore the site now I have transferred the domain to a new hosting company. However, I am getting an error when I try to import the database:
Error
MySQL said: Documentation

#1062 – Duplicate entry ‘1’ for key ‘PRIMARY’

Do I have to rebuild the site from scratch or can someone suggest something – thanks