Same subscription is used for different assets created with API

Summary

Same subscription is used for different assets created with API

Content

Hi,

I used REST API (/fscmRestApi/resources/latest/customerAssets) to create 2 IB assets with the following payloads,

{
      "AssetNumber": "FIT3000-AL1",
      "Description": "FIT 3000 Cardio-Fitness Machine",
      "CustomerId": 300000177639444,
      "CustomerAccountId": 300000177639446,
      "CustomerAccountSiteUseId": 300000177639450,      
      "ItemId": 300000180336424,
      "ItemOrganizationId": 300000047274441,
      "Quantity": 1,
      "ShipmentDate": "2020-03-04T02:13:03+00:00",
      "UpdateContractFlag": "Y"
}

{
      "AssetNumber": "FIT3000-AL2",
      "Description": "FIT 3000 Cardio-Fitness Machine",
      "CustomerId": 300000177639444,
      "CustomerAccountId": 300000177639446,
      "CustomerAccountSiteUseId": 300000177639450,      
      "ItemId": 300000180336424,
      "ItemOrganizationId": 300000047274441,
      "Quantity": 1,
      "ShipmentDate": "2020-03-04T02:13:03+00:00",
      "UpdateContractFlag": "Y"
}

Both payloads are executed successfully. I can see 2 IB assets created. 

After I run Reprocess Installed Base Updates ESS, 1 single subscription is created with 2 products (i.e. included warranty item). Do you know why I don't have 2 subscriptions created for each included warranty product? Can this be configured?