Por que o serviço mostra as notificações no horário errado?

Mobile Android
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#1

Boa noite, eu criei um serviço de notificação para o meu APP, ele deveria exibir as notificações no momento definido, no caso 6h da manhã, porém ele exibe várias vezes durante períodos aleatórios do dia. Alguém pode me ajudar a descobrir o problema? Código:

AndroidManifest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="tk.thallyssonklein.kapp" android:permission="android.permission.RECEIVE_BOOT_COMPLETED">

    <uses-permission android:name="com.android.alarm.permission.SET_ALARM"/>
    <uses-permission android:name="android.permission.RECEIVE_BOOT_COMPLETED"/>

    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:roundIcon="@mipmap/ic_launcher_round"
        android:supportsRtl="true"
        android:theme="@style/AppTheme">

        <activity android:name=".MainActivity">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
        <receiver android:name=".AlarmBroadcastReceiver" android:process=":remote">
        </receiver>
        <receiver android:name=".BootReceiver">
            <intent-filter>
                <action android:name="android.intent.action.BOOT_COMPLETED" />
            </intent-filter>
        </receiver>
        <service android:enabled="true" android:name=".NotificationService" android:label="Notification Service"/>
    </application>

</manifest>

BootReceiver.kt

package tk.thallyssonklein.kapp

import android.content.BroadcastReceiver
import android.content.Context
import android.content.Intent

/**
 * Created by thall on 22/01/2018.
 */
class BootReceiver : BroadcastReceiver(){
    override fun onReceive(p0: Context?, p1: Intent?) {
        val intent = Intent(p0, NotificationService::class.java)
        if (p0 != null) {
            p0.startService(intent)
        }
    }
}

NotificationService.kt

package tk.thallyssonklein.kapp

import android.app.AlarmManager
import android.app.PendingIntent
import android.app.Service
import android.content.Context
import android.content.Intent
import android.content.SharedPreferences
import android.os.IBinder
import android.support.v7.app.AppCompatActivity
import java.util.*

/**
 * Created by thall on 21/01/2018.
 */
class NotificationService : Service(){

    lateinit var preferences: SharedPreferences

    override fun onBind(p0: Intent?): IBinder {
        TODO("not implemented") //To change body of created functions use File | Settings | File Templates.
    }

    override fun onCreate(){
        preferences = getSharedPreferences("tk.thallyssonklein.kapp.notifications", AppCompatActivity.MODE_PRIVATE)
        val alarmManager = getSystemService(Context.ALARM_SERVICE) as AlarmManager
        var id = 0
        for(mov in preferences.all){
            alarmManager.set(
                    AlarmManager.RTC_WAKEUP,
                    Calendar.getInstance().apply {
                        set(Calendar.HOUR_OF_DAY, 6)
                        set(Calendar.MINUTE, 0)
                        set(Calendar.SECOND, 0)
                    }.timeInMillis,
                    PendingIntent.getBroadcast(
                            applicationContext,
                            id,
                            Intent(applicationContext, AlarmBroadcastReceiver::class.java).apply {
                                putExtra("notificationId", id)
                                putExtra("ticker", "A morning exercise")
                                putExtra("title", mov.key)
                                putExtra("text", "Do this exercise now!")
                            },
                            PendingIntent.FLAG_CANCEL_CURRENT
                    )
            )
            ++id
        }
    }
}

AlarmBroadcastReceiver.kt

package tk.thallyssonklein.kapp

/**
 * Created by thall on 14/01/2018.
 */
import android.app.Notification
import android.app.NotificationManager
import android.app.PendingIntent
import android.content.BroadcastReceiver
import android.content.Context
import android.content.Intent

class AlarmBroadcastReceiver : BroadcastReceiver() {
    override fun onReceive(context: Context?, intent: Intent?) {
        (context?.getSystemService(Context.NOTIFICATION_SERVICE) as NotificationManager).notify(
                intent!!.getIntExtra("notificationId", 0),
                Notification.Builder(context).apply {
                    setSmallIcon(tk.thallyssonklein.kapp.R.drawable.ic_stretching_exercises)
                    setContentTitle(intent.getStringExtra("title"))
                    setContentText(intent.getCharSequenceExtra("text"))
                    setWhen(System.currentTimeMillis())
                    setTicker(intent.getCharSequenceExtra("ticker"))
                    setPriority(Notification.PRIORITY_DEFAULT)
                    setAutoCancel(true)
                    setDefaults(Notification.DEFAULT_SOUND)
                    setContentIntent(PendingIntent.getActivity(context, 0, Intent(context, NotificationService::class.java), 0))
                }.build()
        )
    }
}

Eu já tentei de tudo mas não descobri nenhum erro nesse código.