Might just be a spare spade terminal on the main switch.
Sometimes there is a spare terminal which is activated separately at first click of the key, and if the ignition is connected to it will provide fresh new contacts, effectively load shedding, and a functionality some may prefer.
The old ignition terminal can be used for your accessories.
Discovered this when my ignition started acting up, caused by poor contacts in the switch, cured by the simple relocation.
But not all switches are the same, only one out of three I tried are this way.