Marketo REST API - CustomObjects filtering not working as expected

[DavidK]

Filtering CustomObjects with multiple values using the "input" parameter results in duplicate records.

Example:

Executing this request, where the value "myTestLC" is provided twice  results in 3 custom object results, 2 of which are duplicates.

{
  "fields": ["CreatedAt","MarketoGUID","UpdatedAt","Check123"],
  "filterType": "Check123",
  "input": [
    {
      "Check123": "myTestLC"
    },
    {
      "Check123": "myTestLC"
    },
    {
      "Check123": "myTestLC2"
    }
  ]
}

 Results:

{
	"requestId": "5ac3#19136337ab7",
	"result": [
		{
			"seq": 0,
			"marketoGUID": "f2b54589-f283-49cc-a891-e0324fc4ad65",
			"check123": "myTestLC",
			"createdAt": "2024-08-09T08:12:04Z",
			"updatedAt": "2024-08-09T08:12:04Z"
		},
		{
			"seq": 1,
			"marketoGUID": "f2b54589-f283-49cc-a891-e0324fc4ad65",
			"check123": "myTestLC",
			"createdAt": "2024-08-09T08:12:04Z",
			"updatedAt": "2024-08-09T08:12:04Z"
		},
		{
			"seq": 2,
			"marketoGUID": "f1f677bd-0960-4d12-a4e0-f418d4d71b6f",
			"check123": "myTestLC2",
			"createdAt": "2024-08-09T08:12:16Z",
			"updatedAt": "2024-08-09T08:12:16Z"
		}
	],
	"success": true
}

Is this expected behavior that we should consider, or a bug in the API?
Note: other endpoints behave properly when filtering with multiple values and do not return duplicate records.

[SanfordWhiteman]

That's expected behavior. You didn't deduplicate first, so you shouldn't expect deduped results. Some endpoints behave differently from others, but the outcome is unknown if you don't dedupe.