loop-and-copy.js

var xs = { 
  template: [
    {template: 'one', dest: 'two'},
    {template: 'one', dest: 'two'}
  ],
  copy: [
    {template: 'one', dest: 'two'},
    {template: 'one', dest: 'two'}
  ]
};

const copy = ({template, dest}) => {
  return this.fs.copyTpl(
    this.templatePath(template),
    this.destinationPath(dest),
    this.props
  );
}

return Object.keys(xs)
  .map(key => xs[key])
  .reduce((x, y) => [...x, ...y])
  .map(copy);