If for some reason the user doesn't want to shuffle there would be the idea of having the raw selector; shuffling would use SelectorSequential(list(SelectorXxx, SelectorRandom)).
The situation is a bit annoying because this is probably the only reason to have a SelectorSequential at all. Also the number of selected individuals is provided dynamically, so to make SelectorSequential useful at all there would need to be a way to select x * n individuals in step 1, followed by n individuals in step 2.
If for some reason the user doesn't want to shuffle there would be the idea of having the raw selector; shuffling would use SelectorSequential(list(SelectorXxx, SelectorRandom)).
The situation is a bit annoying because this is probably the only reason to have a SelectorSequential at all. Also the number of selected individuals is provided dynamically, so to make SelectorSequential useful at all there would need to be a way to select x * n individuals in step 1, followed by n individuals in step 2.