code: function duplicateVertices(arrays) {
    const newArrays = {};
    Object.keys(arrays).forEach(function(name) {
      const arraySpec = arrays[name];
      const srcArray = getArray(arraySpec);
      const newArraySpec = createArrayOfSameType(arraySpec, srcArray.length);
      copyElements(srcArray, getArray(newArraySpec), 0);
      newArrays[name] = newArraySpec;
    });
    return newArrays;
  }
docs: Creates a duplicate set of vertices
  
  This is useful for calling reorientVertices when you
  also want to keep the original available
  
  @param {module:twgl.Arrays} arrays of vertices
  @return {module:twgl.Arrays} The dupilicated vertices.
  @memberOf module:twgl/primitives