understanding editor join json object elements to populate select list

Can anyone explain the format of json object which is part of editor json to populate select list in editor? For eg I am referring to the json in example: http://editor.datatables.net/release/DataTables/extras/Editor/examples/join.html
ie I couldn't understand the meaning of {
"value": "1",
"0": "1",
"label": "IT",
"1": "IT"
} as in below json which is a part of the below json. I understand that its for populating the select list in the example but what is "0": "1" and "1": "IT"

"dept": [
{
"value": "1",
"0": "1",
"label": "IT",
"1": "IT"
},
{
"value": "2",
"0": "2",
"label": "Sales",
"1": "Sales"
},