Anomaly in the API

Just curious about an API observation.

If I do a GET inverter/{inverter_serial_number}/settings
I retrieve the IDs of all the settings for the inverter, such as...

  }, {
    "id" : "28",
    "name" : "AC Charge 2 Start Time",
    "validation" : "Value format should be HH:mm. Use correct time range for hour and minutes",
    "validation_rules" : [ "date_format:H:i" ]
  }, {
    "id" : "29",
    "name" : "AC Charge 2 End Time",
    "validation" : "Value format should be HH:mm. Use correct time range for hour and minutes",
    "validation_rules" : [ "date_format:H:i" ]
  }, {

However, having played with changing my AC Charge 2 schedule, I revisted the list of settings again and find:

}, {
"id" : "102",
"name" : "AC Charge 2 Start Time",
"validation" : "Value format should be HH:mm. Use correct time range for hour and minutes",
"validation_rules" : [ "date_format:H:i" ]
}, {
"id" : "103",
"name" : "AC Charge 2 End Time",
"validation" : "Value format should be HH:mm. Use correct time range for hour and minutes",
"validation_rules" : [ "date_format:H:i" ]
}, {

Is there some subtle difference between "28" / "102" or perhaps ths is just a defect ?

Is this perhaps firmware related?
The older kit didn't have a second slot (well, ones that worked) whereas later versions now do?
I think the registers underneath moved as part of this, so perhaps this is why the IDs are translated to different ones?

Icarus That's interesting... looking back at an old list of settings I had retrieved (when playing with the API), I see I have both 28 and 102 labelled as "AC Charge 2 Start Time". 102 to 127 are a contiguous group of settings for charge slots 2 through 10. 64 and 65 are slot 1 start end end, and 101 is slot 1's limit.
These don't seem to match the register definitions in givenergy_modbus.

On the subject of the API, is there a difference between 'presets' and 'settings' ? Is that again historical ?