Yes, you have the ability to designate one splunk host as a license master and make other splunk hosts license slaves. The other alternative is to install the license on each host which can be a bit much in a larger deployment. See: http://docs.splunk.com/Documentation/Splunk/6.4.1/Admin/Configurealicensemaster
In theory, since you can install the same license on multiple machines, you could have multiple license masters but a license slave can only be the slave of one license master.
A central license master isn't required. So you could install the same enterprise license on multiple machines. Unless that has changed? @MuS Each host would still be fall under that same license.
I'ed be curious to know how this works as well, I don't see any clear answers on using the same license on potentially different environments that require segregation for security requirements for example.
According your description "In theory, since you can install the same license on multiple machines", my digest is that I can install same one license on multiple master machines. My digest is true?
Yes. What exactly are you trying to accomplish with multiple license masters? You could install the splunk license, for example on two hosts, and configure them both to be license masters BUT any license slaves that you configure would need to point to one or the other, not both. OR if you are looking for failover capabilities, you could try to put a load balancer in front of the two license masters (as an example). Depends on what your usecase is.