There are some connectors in the Rectangular Connectors - Arrays, Edge Type, Mezzanine (Board to Board) category with multiple values for the “Mating Stacking Heights” specification and there seems to be some confusion about this. This does not mean there are separate part numbers with different “height configurations”, but rather there is some tolerance built into the connector to allow different stacked heights. Here is an example that shows this in action:
Manufacturer part number AXK5F70547YG; Digi-Key part number 255-3227-1-ND has a listed rating of 2.0mm and 2.5mm. Page 1 shows a diagram of the mating length, this is one indication that there is some tolerance on how far you can push the connector in or the minimum amount it needs to be inserted.
Page 4 of the datasheet also shows an indication of what some mating heights will look like.
You might think “how do these stay together if there is possibility of vibration?”, the datasheet also covers a recommendation on page 8 for using spacers between boards.
It would be safe to assume that other connectors in this category with multiple ratings have similar recommendations and tolerances on mating height.