Earn 4,500 ($45.00)

I am joining clips like this:

def concatenate_clips(clip_names, video_filename):
    print(clip_names)
    video_streams = []
 
    for name in clip_names:
        input_clip = ffmpeg.input(name)
        video_streams.append(input_clip)
 
    # Concatenate video without audio
    concat_video = ffmpeg.concat(*video_streams, v=1, a=0)
 
    # Save the result (video without audio)
    output = ffmpeg.output(
        concat_video, video_filename,
        pix_fmt='yuv420p', vcodec='libx264'
    )
    output.run()
    return video_filename

However, when I join clips that have been created from GIFs with other .MP4s, I get an infinite frame duplication error:

More than 1000 frames duplicated      0kB time=00:00:00.00 bitrate=N/A speed=   0x

After accepting the bounty, I will share with you the entire source that shows how I am encoding all clips. I believe they need to be encoded in the same way to prevent this error.