On one of my bikes I have a tiny little rack above the front wheel and a Tubus Ergo (discontinued) low rider rack for panniers. The small top rack was made by Nashbar and fit to the canti brake posts. Sunlite also made a rack similar to the Nashbar rack.

In the photo I have my Polartec vest (orange) bundled up and strapped to the top rack.




My point is that in some cases you can have both low rider racks and a top rack. And some manufacturers make a front rack that provides both.