Callbacks in Paging library called multiple times

In may project I am using the Paging library from Android Architecture Components. Data is read from the Room db which is used as a cache and when the end of the list is reached I fetch new data from the network api with Boundary callbacks. Unfortunatelly when new updates are called from the api, it is being called 4 or more times, even with boolean flags in the method so the new data is incorrect.

From database I return Datasource.Factory:

    @Query("SELECT * FROM movieentity ORDER BY popularity DESC")
    fun allMovies(): DataSource.Factory<Int, MovieEntity>

Methods in Repository, basically I want to clear cache and lead next page from the api:

    override fun allMovies(movieBoundaryCallback: 
    MainViewModel.MovieBoundaryCallback): LiveData<PagedList<Movie>> {
        // Get data source factory from the local cache
        val dataSourceFactory = moviesDao.allMovies().map {
            MovieMapper.fromDb(
                it
            )
        }

        val config: PagedList.Config = PagedList.Config.Builder()
            .setInitialLoadSizeHint(DATABASE_PAGE_SIZE)
            .setPageSize(DATABASE_PAGE_SIZE)
            .setPrefetchDistance(0)
            .build()

        // Get the paged list
        return LivePagedListBuilder(dataSourceFactory, config)
            .setBoundaryCallback(movieBoundaryCallback)
            .build()
    }

    override suspend fun refreshMovies(page: Int) {
        withContext(Dispatchers.IO) {
            moviesDao.deleteAll()
            moviesDao.insertAll(*fetchMovies(page).toTypedArray())
        }
    }

The Boundary callback class is defined in ViewModel as innner class:

    val callback = MovieBoundaryCallback()

    // get movies saved in local db
    val movies = getMoviesUseCase.allMovies(callback)

    ...

    inner class MovieBoundaryCallback : PagedList.BoundaryCallback<Movie>() {
        private var lastRequestedPage = 1
        private var isRequestInProgress = false

        private fun refreshMoviesList() {
            if (isRequestInProgress) return

            isRequestInProgress = true
            if (isInternetAvailable(getApplication())) {
                lastRequestedPage++
                try {
                    viewModelScope.launch {
                        getMoviesUseCase.refreshMovies(lastRequestedPage)
                    }
                    isRequestInProgress = false
                } catch (e: Exception) {
                    e.printStackTrace()
                }
            }
        }

        override fun onItemAtEndLoaded(itemAtEnd: Movie) {
            refreshMoviesList()
        }
    }

For RecyclerView's adapter I extend PagedListAdapter. Maybe the problem is because of coroutines?Please help me solve this problem or give a hint. Thanks in advance.