diff --git a/README.md b/README.md
index a7a7d92..fa413cf 100644
--- a/README.md
+++ b/README.md
@@ -16,8 +16,6 @@ deb http://mirror.ctdn.net/ubuntu focal-backports main restricted universe multi
 deb http://mirror.ctdn.net/ubuntu focal-security main restricted
 deb http://mirror.ctdn.net/ubuntu focal-security universe
 deb http://mirror.ctdn.net/ubuntu focal-security multiverse
-deb http://mirror.ctdn.net/ubuntu-security focal-security multiverse
-deb http://mirror.ctdn.net/ubuntu-security focal-security multiverse
 
 deb [arch=amd64 signed-by=/usr/share/keyrings/docker-archive-keyring.gpg] http://mirror.ctdn.net/docker focal stable
 deb [arch=amd64] http://mirror.ctdn.net/msedge stable main