Resize, crop and SBS duplicate with ffmpeg
Use

ffmpeg -i video.mp4 -filter_complex \
       "[0]scale=iw*sar:ih,setsar=1,scale=-1:960,crop=960:960,split[left][right]; \
        [left][right]hstack[sbs]"  -map "[sbs]" -map 0:a? out.mp4