In Page DocType why is change event called twice?

Hello,

I have create a Page DocType.

In this page I have place the code

let inspection_status = page.add_field({
		label: 'Inspection Status',
		fieldtype: 'Select',
		fieldname: 'inspection_status_list',
        //default: 'All',
		options: [
			'All',
			'Pending',
			'Completed'
		],
		change() {
			frappe.msgprint(inspection_status.get_value());
		}
	});

But when a user selects an item the Select's change event is called twice.

Why is this happening?

Will this affect performance as I am fetching a lot of data using multiple joined SQL statement?

TIA

Yogi Yang