You should not have overlapping IP space assigned to interfaces anywhere in your network. When you try to do this on two interfaces on the same router, you'll get the message you mentioned.
IP addresses should be unique across all devices and interfaces on your network. (Unless you use some kind of NAT translation).
10.10.10.0/30 is a subnet of 10.10.0.0/16. You might be confusing this scenario with the concept of route summarization. You could have 10.10.10.0/30 on an interface on the router, and then have a routing protocol, such as OSPF summarize the announce of the route as 10.10.0.0/16.