We have Cryptowall on our main PC and have a recent image on external drive. 

We want to make rescue CD from 2nd PC and can not install V6, asking for V5 Key and when i enter V5 key I get:

"Licence key already upgraded"

can we make a restore CD from free version or trial for now?

we did pay for 2 seats with V6 workstation. 

infected PC is Win7, Image is on network Win10 PC. 

we were able to make restore CD from trial version and make Win10 PE restore CD, found image in Reflect folder on network.

Restore worked from restore CD made from trial version. all is well. Still would like to register V6. 

we were never able to install our licence key for Version 6, the message is "licence key already updated"

any chance we can get some help on this?

I would probably contact support to refresh the key. It might be quicker.
http://macrium.com/support.aspx#tickets