Separate Lists by Z Coordinate when number per sublist varies

[Joseph_Oster]

This example of MIndex finds points with the same X and Y values, differing only in Z, but you can easily adapt it to find duplicate Z values:

Set Member Index Example (MIndex)

There can be precision issues that require rounding, as explained here:

Select similar geometries and assign them into the same layer

It looks to me like you’ve done everything correctly (though I haven’t bothered to figure out why you have two MIndex components instead of just one), and are running into a rounding precision issue caused by the extremely small volume values: 0.0000242 To 0.0000343 This is evident when you examine the panel labeled “set” (below) and see duplicate values. The purple group offers a switch between “raw” (as it was) and “fixed”, which multiplies all volume values by ten thousand and rounds to ‘rD…