call done() multiple times breaks tests workflow

[AlexeyKhristov]

If done() function called multiple times - should() function called several times or never called at all, depends on previous flow.

My expectations - receive mocha like error: "Uncaught Error: done() called multiple times" or second call have no effect at all

Broke cases:
Case 1:

"use strict";
var expect = require("chai").expect;
var machiatto = require("machiatto");
var spec = machiatto("check flow tests");

spec
  .when('async when', function (context, done) {
    setTimeout(done, 1000);
    setTimeout(done, 2000);
  })
  .should('should N1', function (context) {
    console.log('should N1');
    expect(true).to.be.ok;
  })
  .should('should common', function (context) {
    console.log('should common');
    expect(false).to.be.false;
  });

module.exports = spec;

I expect what should "should N1" called once and should "should common" called once.
Result - "should N1" called twice, "should common" never called

Case 2:

"use strict";

var expect = require("chai").expect;
var machiatto = require("machiatto");
var spec = machiatto("check flow tests");

spec
  .when('async when', function (context, done) {
    setTimeout(done, 1000);
    setTimeout(done, 2000);
  })
  .should('should N1', function (context) {
    console.log('should N1');
    expect(true).to.be.ok;
  })
  .should('should common', function (context) {
    console.log('should common');
    expect(false).to.be.false;
  });

spec
  .when('async when', function (context, done) {
    setTimeout(done, 2000);
  })
  .should('should N2', function (context) {
    console.log('should N2');
    expect(true).to.be.ok;
  })
  .should('should common', function (context) {
    console.log('should common');
    expect(false).to.be.false;
  });

module.exports = spec;

In this case I expect "should 2" and "should common" called one time, but
result is: "should common" called twice and "should N2" never called. Additionally but with "should 1" repeated