Short answer is no. Roon’s license is for one active Core at a time. Two active Cores at the same time requires two Roon licenses. Also, one can not share a library from one license to the other license.
Of course, as you realize, one can have as many Cores as one cares to, but only one active at a time and the others dormant.
Roon’s library is specific to the machine that Core is running on. Different Core machines mean different libraries. To keep the libraries in sync, one needs to do Backups and Restores using Roon’s Settings==>Backup menus.
As long as both licenses are to the same Account, then you can indeed backup and restore between the cores. It is when you have two licenses with two different accounts that you cannot restore between them.