There are few scenarios where IIS shows that there are additional Symantec Endpoint Encryption Services_1XXXXXXX8 Site has been added post upgradation from 11.4.0 MP1 HF1 to SEEMS 12.0.1
As we had recently moved to .net core this is a stale entry which is not getting cleaned up. You can right click and delete this stale entry. There is no impact on any encryption services.