JSFiddle - React, Tailwind, and code Playground

HTML

<div ng-app="app">
    <div ng-controller="MainController">
        <select id="typeselect" ng-options="accnts.type for accnts in jsonmarkers | unique:'type'" ng-model="accnt" ng-change="changeaccnt(accnt.type)" multiple></select>
    </div>
</div>

JavaScript

var app = angular.module("app", []);

app.controller("MainController", function ($scope) {
    $scope.jsonmarkers = [{
        "name": "Jeff",
            "type": "Organisation + Training Entity",
            "userID": "1"
    }, {
        "name": "Fred",
            "type": "Organisation + Training Entity",
            "userID": "2"
    }];
});


app.filter('unique', function () {

    return function (items, filterOn) {

        if (filterOn === false) {
            return items;
        }

        if ((filterOn || angular.isUndefined(filterOn)) && angular.isArray(items)) {
            var hashCheck = {}, newItems = [];

            var extractValueToCompare = function (item) {
                if (angular.isObject(item) && angular.isString(filterOn)) {
                    return item[filterOn];
                } else {
                    return item;
                }
            };

            angular.forEach(items, function (item) {
                var valueToCheck, isDuplicate = false;

                for (var i = 0; i < newItems.length; i++) {
                    if (angular.equals(extractValueToCompare(newItems[i]), extractValueToCompare(item))) {
                        isDuplicate = true;
                        break;
                    }
                }
                if (!isDuplicate) {
                    newItems.push(item);
                }

            });
            items = newItems;
        }
        return items;
    };
});