Postage shown on all line items

[BrookeCamov]

On orders with multiple items from the same retailer (so the same invoice number on all line items) , postage is shown on every line item, however it is only charged once, which produces incorrect reporting.

Order #31850 it's all from the same retailer, so there should only be one postage amount.

https://www.bikeexchange.com.au/administration/line_items?utf8=%E2%9C%93&commerce_line_item_report%5Bcreated_at%5D=&commerce_line_item_report%5Border_id%5D=31850&commerce_line_item_report%5Binvoice_id%5D=&commerce_line_item_report%5Binvoice_status%5D=&commerce_line_item_report%5Boutstanding%5D=0&commerce_line_item_report%5Brequires_remittance_vetting%5D=0&commerce_line_item_report%5Bstatus%5D=&commerce_line_item_report%5Bdelivery_type%5D=&commerce_line_item_report%5Badvert_title%5D=&commerce_line_item_report%5Bemail_businessname%5D=&commerce_line_item_report%5Bcoupon_used%5D=0&commerce_line_item_report%5Bcoupon%5D=&commerce_line_item_report%5Border_names%5D=&commerce_line_item_report%5Border_email_address%5D=&commerce_line_item_report%5Border_phone%5D=&commerce_line_item_report%5Border_ip_address%5D=&button=

Order #37644, is to 2 different retailers, so there should be 2 postage amounts shown (provided the retailer charges postage)

https://www.bikeexchange.com.au/administration/line_items?utf8=%E2%9C%93&commerce_line_item_report%5Bcreated_at%5D=&commerce_line_item_report%5Border_id%5D=37644&commerce_line_item_report%5Binvoice_id%5D=&commerce_line_item_report%5Binvoice_status%5D=&commerce_line_item_report%5Boutstanding%5D=0&commerce_line_item_report%5Brequires_remittance_vetting%5D=0&commerce_line_item_report%5Bstatus%5D=&commerce_line_item_report%5Bdelivery_type%5D=&commerce_line_item_report%5Badvert_title%5D=&commerce_line_item_report%5Bemail_businessname%5D=&commerce_line_item_report%5Bcoupon_used%5D=0&commerce_line_item_report%5Bcoupon%5D=&commerce_line_item_report%5Border_names%5D=&commerce_line_item_report%5Border_email_address%5D=&commerce_line_item_report%5Border_phone%5D=&commerce_line_item_report%5Border_ip_address%5D=&button=