color loss and image duplication when using xfade to merge two videos.

my platform version is:

<dependency>
            <groupId>org.bytedeco</groupId>
            <artifactId>javacv-platform</artifactId>
            <version>1.5.9</version>
</dependency>

my code is as follow (i learned from #1776 ):

    public static void main(String[] args) throws FFmpegFrameGrabber.Exception, FFmpegFrameRecorder.Exception, FFmpegFrameFilter.Exception {
        String out = "/home/hxl/vlogdemo/" + new SimpleDateFormat("MMdd-HHmmss'.mp4'").format(new Date());
        String inputFilePath = "/home/hxl/vlogdemo/1.mp4";
        String inputFilePath2 = "/home/hxl/vlogdemo/2.mp4";
        FFmpegLogCallback.set();
        FFmpegFrameGrabber grabber = new FFmpegFrameGrabber(inputFilePath);
        grabber.start();
        FFmpegFrameGrabber grabber2 = new FFmpegFrameGrabber(inputFilePath2);
        grabber2.start();

        FFmpegFrameFilter filter = new FFmpegFrameFilter(
                "[0:v][1:v]xfade=transition=wipeleft:offset=5s:duration=2[v]",
                grabber.getImageWidth(), grabber.getImageHeight());
        filter.setPixelFormat(grabber.getPixelFormat());
        filter.setSampleFormat(grabber.getSampleFormat());
        filter.setVideoInputs(2);
        filter.setImageHeight(grabber.getImageHeight());
        filter.setImageWidth(grabber.getImageWidth());
        filter.start();
        FFmpegFrameRecorder recorder = new FFmpegFrameRecorder(out, grabber.getImageWidth(), grabber.getImageHeight());
        recorder.setVideoCodec(avcodec.AV_CODEC_ID_H264); 
        recorder.setFormat("mp4"); 
        recorder.setAudioBitrate(grabber.getAudioBitrate());
        recorder.setVideoBitrate(grabber.getVideoBitrate());
        recorder.setFrameRate(grabber.getFrameRate());
        recorder.setAudioChannels(grabber.getAudioChannels());
        recorder.setSampleRate(grabber.getSampleRate());
        recorder.start();
        Frame frame1, frame2, frame;
        while ((frame1 = grabber.grabImage()) != null && (frame2 = grabber2.grabImage()) != null) {
            filter.push(0, frame1);
            filter.push(1, frame2);
            frame = filter.pullImage();
            if (frame != null && frame.image != null) {
                recorder.record(frame);
            }
        }
        grabber.stop();
        grabber2.stop();
        filter.stop();
        recorder.stop();
        System.out.println("finish");
    }

and the output video is like this: my first video: and my second video:

why does color lose?and why dose image duplicated?