在更新ubuntu时，出现这个错误：

Hit:1 http://mirrors.aliyun.com/ubuntu bionic InRelease                        
Hit:2 https://download.docker.com/linux/ubuntu bionic InRelease                
Hit:3 http://mirrors.aliyun.com/ubuntu bionic-updates InRelease            
Hit:4 http://mirrors.aliyun.com/ubuntu bionic-backports InRelease              
Hit:5 http://mirrors.aliyun.com/ubuntu bionic-security InRelease               
Hit:6 http://mirrors.aliyun.com/ubuntu bionic-proposed InRelease               
Reading package lists... Done
W: Target Packages (restricted/binary-amd64/Packages) is configured multiple times in /etc/apt/sources.list:5 and /etc/apt/sources.list:54
W: Target Packages (restricted/binary-i386/Packages) is configured multiple times in /etc/apt/sources.list:5 and /etc/apt/sources.list:54
W: Target Packages (restricted/binary-all/Packages) is configured multiple times in /etc/apt/sources.list:5 and /etc/apt/sources.list:54
W: Target Translations (restricted/i18n/Translation-en_US) is configured multiple times in /etc/apt/sources.list:5 and /etc/apt/sources.list:54
W: Target Translations (restricted/i18n/Translation-en) is configured multiple times in /etc/apt/sources.list:5 and /etc/apt/sources.list:54
W: Target DEP-11 (restricted/dep11/Components-amd64.yml) is configured multiple times in /etc/apt/sources.list:5 and /etc/apt/sources.list:54

根据错误提示，是在
/etc/apt/sources.list的第5行
与
/etc/apt/sources.list的第54行
重复。删掉一个就好了。

apt-get更新错误