Due to such high demand for the game, some of the servers are being cloned to allow more room for the players.  There are three Core clones, as well as an RP and RvR clone:

As mentioned by Mark in this post:

http://herald.warhammeronline.com/warherald/NewsArticle.war?id=292

We will be cloning 5 servers in order to improve player experiencing on servers with high populations.

Click the "More..." link below to read the list of servers cloned!

Once the copies are made the two servers are entirely separate, if you choose to play on the new server any achievements earned there will not carry over to the previous server and vice versa. You will always be able to return to your character on either server at any time.

Below are the servers being cloned and the names of the new ones they are being copied to, these servers will maintain the same ruleset as their parent:

Phoenix Throne (RP) => White Tower (RP)

Skull Throne (Core) => Tower of Doom (Core)

Volkmar (Core) => Magnus (Core)

Badlands (Core) => Mordheim (Core)

Dark Crag (RvR) => Eerie Downs (RvR)

The cloning process will require several hours of downtime, Phoenix Throne will be cloned first, our anticipated downtime is approximately 7AM EDT this morning. We will then begin cloning the other servers once Phoenix Throne and White tower have been brought back online.

A new herald post will be created for both of these maintenance windows. Thank you and as always watch the Herald for important news and information!