Hello Makazore!
Yes, you can certainly have multiple primary sites on a domain. I would suggest setting it up in the typical primary child site method. This allows you to perform all your admin from the central site (top site of the hierarchy).
If you don't have or keep a clean and organized AD, you should consider using IP subnets and/or IP address ranges for the boundaries. You may have to work with your organizations network team to properly identify what IP subnets/ranges associate to site server 1 versus site server 2. In the end, you will have two sites for your ConfigMgr clients to point to.
Cheers
