If you haven't told it to output progress information or verbosely report what files have been copied, between the duplicates that it feels the need to report, it doesn't have anything to say.
It's copying things over a network, so there will be some tiny pauses now and then, but they shouldn't be for very long - just like sometimes when you're loading a web page, it'll take a little longer than others.
If you want to make sure it's still doing stuff and you don't want to stop it to restart it with a -v option, you can open another terminal window and run top. That should show how much CPU and memory it's taking up, and as time passes, you should be seeing that the total amount of CPU time it's used is going up.
Another way to see that it's doing stuff is to install and run iotop. It does much the same thing as top, except that it's looking at how much activity is going on with your storage devices and network devices. Unlike top, iotop requires root or NET_ADMIN privileges to run because the network input and output operations of processes are only measurable by root, and most if not all storage I/O is only viewable by the process owner and root. The current code does not even bother to show the subset it can without the needed privilege.
That should be enough. I hope that was enough.