Why does my custom shipping rate app remove duplicated service codes?

Having custom shipping rates App return following rates, which contains two rates having same service code and same price but different service name

[
{
“currency”: “AUD”,
“phone_required”: true,
“service_name”: “Pickup - Broadmeadows, VIC”,
“description”: “”,
“service_code”: “25032-15”,
“total_price”: 0
},
{
“currency”: “AUD”,
“phone_required”: true,
“service_name”: “Express Delivery”,
“description”: “”,
“service_code”: “34995-15”,
“total_price”: 5999
},
{
“currency”: “AUD”,
“phone_required”: true,
“service_name”: “Specialised Delivery”,
“description”: “”,
“service_code”: “34261-15”,
“total_price”: 21276
},
{
“currency”: “AUD”,
“phone_required”: true,
“service_name”: “Regular Delivery”,
“description”: “”,
“service_code”: “34995-15”,
“total_price”: 5999
}
]

however when it appears in checkout the last rate was gone, it is from shopify that remove the rate with duplicated service_code or total price. Can anyone confirm with this? Thanks