Hi freeciv,
As I indicated in my other post, every legal user has unique keys for each of the products. If you get the message that you showed, it means that someone else has already registered that key.
There is one other possibility: The registration system may be off-line for maintenance, but I would expect a more meaningful message in that case.
If someone else has already registered your keys, it usually means that either you or he has an illegal copy. There are many sources of cracked or stolen keys on the Internet.
It is strange that all of the keys for the different products are in use. The one circumstance that I can think of to explain that would be downloading from the link posted by ibcheezin (David Ludwig).
In any case, Fred should be able to sort it.
Regards,
Marty