The idea of running in parallel is also interesting, but it would require Awesome Miner to understand which GPU's are identical in terms of memory and clock to make it fair.
Fair point.
Maybe you could leave that up to the user.
Simplest solution: Run X parallel benchmarks on GPU 1 to X. (where you somehow select X)
More advanced: select specific GPUs to run the benchmark.
Maybe instead of having a "ComboBox" to select a single GPU (or all), make it more like a "CheckBoxComboBox" to allow multiple selections.
This could also allow the user to run "normal" benchmarks on several specific GPUs.