I’m actually no longer sure I completely understand what you are trying to achieve, could you post the code you’re using to generate the plot?
I’m a bit confused because I don’t think the order used by default for the x axis is alphabetical so I wanted to make sure I understand the issue.
Related to this, we could probably allow to use groupedbar(["a", "a", "b", "b"], [1,2,3,4]) to give the same plot as groupedbar(["a", "b"], [1 2; 3 4]), currently it errors.