.mp3 file uploading convert to .mpga

Hey guys, if i upload mp3 file, why its auto convert to .mpga file?

here is my code

public function addTrack($id, Request $request)
    {
        $this->validate($request, [
            'files' => 'required'
        ]);

        $album = $this->albumRepo->findAlbumById($id);
        $files = $request->file('files');

        if($request->hasFile('files')) {
            $getid3 = new \getID3();

            foreach ($files as $key => $file) {


                $file_name = preg_replace('/\.[^.\s]{3,4}$/', '', $file->getClientOriginalName());
                $extension = $file->getClientOriginalExtension();
                $albumName = str_slug($album->name).'_'.$album->id;
                $path = $file->store('track_files/'.$albumName);

                $analyze = $getid3->analyze($path);

                $album->tracks()->create([
                    'name' => $file_name,
                    'slug' => str_slug($file_name),
                    'number' => ++$key,
                    'popularity' => 50,
                    'path' => $path,
//                    'duration' => $analyze['bitrate'],
//                    'playtime' => $analyze['playtime_string'],
                ]);
            }
        }

        return redirect()->back()->with('message', trans('store'));
    }

Thank you