I have bought a domain at unoeuro.com.
I also have my other domain there: nordicrace.dk
I have moved my server for nordicrace.dk to you and want to do the same with my new domain ultrasolutions.dk.

How do I do that?
I have to use Wordpress on ultrasolutions.dk as I also do on nordicrace.dk

I already have a droplet for nordicrace.dk, can I use the same for my new domain?

Just to be clear, my new domain should not replace the old one. We just need to different websites.