The burn address given by the getinfo API is the same for all nodes. There's no fundamental technical barrier to creating more burn addresses, but we have not currently implemented this in the MultiChain software. To create a burn address, you just need to create an address that does not have a corresponding private key, but which still looks valid from the perspective of that blockchain. This page can help:
https://www.multichain.com/developers/address-key-format/