title: Why is livedata observe triggered twice?
body: <p>I have a livedata object that I call on my fragment. First time works fine, it only tiggers just one time, but second time I enter the fragment it triggers twice and don't understand why.</p>
  <p>This is where I call the observe:</p>
  <pre><code>override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?, savedInstanceState: Bundle?): View {
      return inflater.inflate(R.layout.activity_train_with_famous_detail, container, false)
  }
  
  override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
      super.onViewCreated(view, savedInstanceState)
      setupUi(view)
      (activity as TrainingWithFamousActivity).hideToolbar()
      setupListCategoryVideos(view)
      viewModel.getVideosData()
      viewModel.videosData.observe(viewLifecycleOwner, Observer {
          //second time I enter the fragment it triggers his twice
          videoCategoryAdapter.loadItems(it)
      })
      viewModel.videoSelected?.let { loadTrainWithFamousDetailsData(it) }
  }
  </code></pre>
  <p>And this is the method in my view model:</p>
  <pre><code>val videosData = MutableLiveData&lt;List&lt;DtoCelebrityResource&gt;&gt;()
  fun getVideosData() {
      showLoader()
  
      trainingWithFamousUseCase
          .build(this)
          .executeWithError({
              videosData.value = it
              hideLoader()
          }, {
              hideLoader()
          })
  }
  </code></pre>