Network stats doubled(plused) on Android

Hello.I recently found that my network activity indicator in status bar is a bit weired when i use shadowsocks,especially when download big files with it.I saw unkown upload speed ,and the download speed was too fast than usuall which like the upload speed was plused into it.shadowsocks said it’s 680 kb/s but the download speed was about 3Mb/s.that’s pretty weird and only happens when shadowsocks is working.