为什么安卓闹钟设置一个闹钟，会返回两个一样的。

代码如下
public void onCheckedChanged(CompoundButton buttonView,
boolean isChecked) {
if (isChecked) {
Calendar currentTime = Calendar.getInstance();
//创建一个TimePickerDialog实例，并显示
new TimePickerDialog(MainActivity.this, 0,
new TimePickerDialog.OnTimeSetListener() {

                            @Override
                            public void onTimeSet(TimePicker view, int hourOfDay, int minute) {
                                //指定启动AlarmActivity组件
                                Intent intent = new Intent(MainActivity.this, AlarmActivity.class);
                                //创建PendingIntent对象                             
                                PendingIntent pi = PendingIntent.getActivity(MainActivity.this, 0, intent, 0);
                                Calendar c = Calendar.getInstance();
                                c.setTimeInMillis(System.currentTimeMillis());
                                c.set(Calendar.HOUR, hourOfDay);
                                c.set(Calendar.MINUTE, minute);

                                alarmManager.set(AlarmManager.RTC_WAKEUP, c.getTimeInMillis(), pi);
                                Toast.makeText(MainActivity.this, "设置闹钟成功", Toast.LENGTH_SHORT).show();
                            }
                }, currentTime.get(Calendar.HOUR_OF_DAY), currentTime.get(Calendar.MINUTE), false).show();
            }

            else {

            }

        }



        AlarmActivity.java:

        package com.example.financesetting;

import android.app.Activity;
import android.app.AlertDialog;
import android.content.DialogInterface;
import android.content.DialogInterface.OnClickListener;
import android.media.MediaPlayer;
import android.os.Bundle;

public class AlarmActivity extends Activity {
MediaPlayer alarmMusic;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_alarm); 
    alarmMusic = MediaPlayer.create(this, R.raw.sqbm);
    alarmMusic.setLooping(true);
    alarmMusic.start();
    new AlertDialog.Builder(AlarmActivity.this).setTitle("闹钟")
            .setMessage("该记账啦！")
            .setPositiveButton("停止", new OnClickListener() {

                @Override
                public void onClick(DialogInterface dialog, int which) {
                    // 停止音乐
                    alarmMusic.stop();
                    AlarmActivity.this.finish();

                }
            }).show();
}

}

请大神帮忙解答