Caesar's Palace, The Caesars, The Twelve Caesars - they're all the same group. They go by different names depending on location - Twelve Caesars in most of Scandinavia, The Caesars in North America, and Caesar's Palace in Sweden, most of europe, and the rest of the world.
They currently have five albums:
39 Minutes of Bliss (as The Caesars)
Paper Tigers (as The Caesars)
Youth Is Wasted On The Young (as The Twelve Caesars)
Cherry Kicks (as Caesar's Palace)
Love For The Streets (as Caesar's Palace)
I hope this helps clarify some things.
I give EVERY SINGLE ALBUM five out of five stars - great vocals, great leads, great base, great melodies, great everything. If you like rock, don't pass this up.