New Twiddle

controllers.application.js

import Ember from 'ember';

export default Ember.Controller.extend({
  appName: 'Ember Twiddle',
  
  init() {
    this.set('goodModel', false);
    this.set('badModel', false);
  },
  
  actions: {
    updateGoodFit(value) {
      if(!this.get('goodModel') === true) {
        this.set('goodModel', value);
        this.set('badModel', !value);
      }
    },

    updateBadFit(value) {
      if(!this.get('badModel') === true) {
        this.set('badModel', value);
        this.set('goodModel', !value);
      }
    }
  }
});

templates.application.hbs

<input type="checkbox" name='re' checked={{goodModel}} onchange={{action "updateGoodFit" value="target.checked"}}>
<input type="checkbox" name='re' checked={{badModel}} onchange={{action "updateBadFit" value="target.checked"}}>

twiddle.json

{
  "version": "0.10.6",
  "EmberENV": {
    "FEATURES": {}
  },
  "options": {
    "use_pods": false,
    "enable-testing": false
  },
  "dependencies": {
    "jquery": "https://cdnjs.cloudflare.com/ajax/libs/jquery/1.11.3/jquery.js",
    "ember": "2.9.0",
    "ember-data": "2.9.0",
    "ember-template-compiler": "2.9.0",
    "ember-testing": "2.9.0"
  },
  "addons": {}
}