I am wanting to have my books available at work and home, but since my home computer is already registered to me, it is not allowing me to authorize/register my work computer. I get the message that the ID is taken and cannot be used. I though I could have up to 6 devices under my name!!
You should be able to use the same "adobe id" to authorize bot your home and work desktops.
Launch ADE and press "Ctrl + shift + I" and check the Authorization information. If it is not authorized which most probably is the case.
Can you provide the step wise details of the workflow you followed for registering on the desktops? Also provide the exact error message you are getting?