As you see in the pic, the bottom sublists 10 and 11 are not in the correct order (29,31,33 should come after 20,22,24). The sublists are sorted correctly based on the 0 index, but after this I want it to sort by the 1 index.
What is the best way to do this?

group , sort and flatten
first use GroupByKey node to group values by first index, MHDP-1 , then use SortByKey node to sort every group by second index, now use flatten to remove grouping with the desired sorting you want
Thank you! That’s it. I saw a similar answer here. How to Sort by Name THEN Number?