Scheduler running strange

Hello I have a really strange issue in scheduler, sometimes runs the same task for two or three times.. I don't really know what is happening, if there is a server issue or anything else...

This is my simple scheduler code:

<?php

namespace App\Console;

use Illuminate\Console\Scheduling\Schedule;
use Illuminate\Foundation\Console\Kernel as ConsoleKernel;

class Kernel extends ConsoleKernel
{
    /**
     * The Artisan commands provided by your application.
     *
     * @var array
     */
    protected $commands = [

    ];

    /**
     * Define the application's command schedule.
     *
     * @param  \Illuminate\Console\Scheduling\Schedule  $schedule
     * @return void
     */
    protected function schedule(Schedule $schedule)
    {
        
        $schedule->call(function () {
            return true;
        })->everyMinute()->emailOutputTo('...')->thenPing('https://cronhub.io/ping/af709030-c0e8-11e8-9b2f-ff58704a871a');

    }

    /**
     * Register the commands for the application.
     *
     * @return void
     */
    protected function commands()
    {
        $this->load(__DIR__.'/Commands');

        require base_path('routes/console.php');
    }


}

The last outputs was:

And the issue is when running scheduler at a digital ocean server, if I run it locally no problems. Any ideas?

19.06
19.07
19.08
19.09
19.10
19.11
19.12
19.13

19.16
19.16
19.16

19.17
19.18

19.21
19.21
19.21

19.22
19.23

19.25
19.25

19.26