Sovrin can use multiple DID.
DID means that owner's public key address.
I have question that.
Possible multiple DID means does the onwer have multiple public key?
Or does the single public key have multiple DID?
If owner haver multiple public key at this time, Why is DID better than simply using multiple public keys?
Yes. You can have many DIDs and therefore many public keys. The main benefit of DID is that you can eventually rotate your public-private key pair. So, if your counterparty knows your DID it can resolve DID Document with an updated keypair. How the DID Document resolution works depends on a particular DID Method.