600Mbps is an IEEE, wireless chip manufacturer theoretical DATA RATE. Not real in any way. What you will be able to get is the more realistic 85-125Mbps (depending on your environment) THROUGHPUT.
That would be 85-125Mbps on 2.4GHz and 85-125Mbps on the 5GHz bands.
But this it is not 170-250Mbps.
Using the 2.4GHz and 5GHz bands at the same time is much like driving two cars next to each other, not riding in a bus.
Until somebody writes some software to make the adapters split a payload and send it on the two bands at the same and then rebuild the payload at the other end, it ain't happening.