The same table has been defined more than once.

How to fix

Ensure that you have defined each table only once.

Problem example:

{
  "tables": [
    {
      "schema": "Person",
      "name": "Address",
      "columns": [
        {
          "name": "City",
          "deterministic": false,
          "maxLength": 15
        }
      ]
    },
    {
      "schema": "Person",
      "name": "Address",              // Duplicate table definition
      "columns": [
        {
          "name": "AddressLine1",
          "dataset": "AddressesUnique",
          "deterministic": false
        }
      ]
    }
  ]
}

Ensure that you have defined each table only once:

{
  "tables": [
    {
      "schema": "Person",
      "name": "Address",              // Single table definition
      "columns": [
        {
          "name": "City",
          "deterministic": false,
          "maxLength": 15
        },
        {
          "name": "AddressLine1",
          "dataset": "AddressesUnique",
          "deterministic": false
        }
      ]
    }
  ]
}