Multiselectbox field has a "Size" special property that used to control the number of items shown at a time in the field (but since those fields use the list-picker component, it's probably not the case anymore).
Open list field has a "Hint" special property that controls a hint sentence that is shown to tell people what they should write in the input.

Both of those special properties are NOT duplicated when creating a new tracker from a source tracker, which means they will get their default value instead of the one from the source tracker