PO with different GST rates

Single PO - 2 different GST rates-Supply & Labour service

While we will buy AC Machine (GST rate 28%) -seller also requires to dismantle certain old equipments and install this new one with labour supply (GST rate 18%). Now vendor cum dealer wants 2 different Purchase Orders because of 2 different GST rates, Accounts Dept refuse to subscribe to this idea. They want single Purchase Order. Kindly advise whether split PO is required for supply and service part Rgds Jayanta Howrah 29.6.21