Yaml format to represent two different objects in an array

Hi All,

  I am trying to prepare a Swagger file in YAML format for a request JSON for our API. In our JSON there is an array in below format,

"RawParams": [
           {
              "Key": "CSClientLastName",
              "Value": "Stanford"
           },
          {
             "ElementType": "OFIAccountName",
             "ElementList": [
                     {
                        "Key": "ClientFullName",
                        "Value": "Smith D Rogers"
                    },
              ]
         }
],

RawParams is an array with Key/Value object and ElementType/ElementList objects separately embedded. So, how to represent this in YAML format? I tried to define as below but Swagger UI throwing error when I defined items twice with "duplicate error". 

RawParams:
  type: array
  items:
    type: object
    properties:
        Key:
            type: string
        Value:
            type: string

   items:

     type: object

     properties:

        ElementType:
            type: string
        ElementList:
            type: array
            items:
              type: object
              properties:
                  Key:
                       type: string
                  Value:
                       type: string

Could some one please help me?

Thanks,

Durga Prasad