Package multiresolver allows you to Dial to multiple hosts/IPs as a single ClientConn.
Make sure to import this package:
import _ "github.com/Jille/grpc-multi-resolver"
and then you can use it with grpc.Dial():
grpc.Dial("multi:///127.0.0.1:1234,dns://example.org:1234")
Note the triple slash at the beginning.
Note: The ServiceConfig and Attributes from the first target are used, the rest are ignored.