diff --git a/docker/Dockerfile b/docker/Dockerfile
index d7797f5..ac68022 100644
--- a/docker/Dockerfile
+++ b/docker/Dockerfile
@@ -18,10 +18,10 @@ ENV ROS_DISTRO=${ROS_DISTRO}
 RUN test -n "$ROS_DISTRO" || (echo "missing build-arg: ROS_DISTRO" && false)
 RUN apt-get update && \
     apt-get install -y curl gnupg && \
-    if [[ "$ROS_DISTRO" == "noetic" ]]; then \
+    if [[ "$ROS_DISTRO" == "noetic" ]] && ! cat /etc/apt/sources.list /etc/apt/sources.list.d/* | grep "http://packages.ros.org/ros/ubuntu $(. /etc/os-release && echo $UBUNTU_CODENAME) main"; then \
         apt-key adv --keyserver hkp://keyserver.ubuntu.com:80 --recv-keys C1CF6E31E6BADE8868B172B4F42ED6FBAB17C654 && \
         echo "deb http://packages.ros.org/ros/ubuntu focal main" > /etc/apt/sources.list.d/ros1-latest.list ; \
-    else \
+    elif ! cat /etc/apt/sources.list /etc/apt/sources.list.d/* | grep "http://packages.ros.org/ros2/ubuntu $(. /etc/os-release && echo $UBUNTU_CODENAME) main"; then \
     	curl -sSL https://raw.githubusercontent.com/ros/rosdistro/master/ros.key -o /usr/share/keyrings/ros-archive-keyring.gpg && \
     	echo "deb [arch=$(dpkg --print-architecture) signed-by=/usr/share/keyrings/ros-archive-keyring.gpg] http://packages.ros.org/ros2/ubuntu $(. /etc/os-release && echo $UBUNTU_CODENAME) main" | tee /etc/apt/sources.list.d/ros2.list > /dev/null ; \
     fi && \
@@ -164,10 +164,10 @@ ENV ROS_DISTRO=${ROS_DISTRO}
 RUN test -n "$ROS_DISTRO" || (echo "missing build-arg: ROS_DISTRO" && false)
 RUN apt-get update && \
     apt-get install -y curl gnupg && \
-    if [[ "$ROS_DISTRO" == "noetic" ]]; then \
+    if [[ "$ROS_DISTRO" == "noetic" ]] && ! cat /etc/apt/sources.list /etc/apt/sources.list.d/* | grep "http://packages.ros.org/ros/ubuntu $(. /etc/os-release && echo $UBUNTU_CODENAME) main"; then \
         apt-key adv --keyserver hkp://keyserver.ubuntu.com:80 --recv-keys C1CF6E31E6BADE8868B172B4F42ED6FBAB17C654 && \
         echo "deb http://packages.ros.org/ros/ubuntu focal main" > /etc/apt/sources.list.d/ros1-latest.list ; \
-    else \
+    elif ! cat /etc/apt/sources.list /etc/apt/sources.list.d/* | grep "http://packages.ros.org/ros2/ubuntu $(. /etc/os-release && echo $UBUNTU_CODENAME) main"; then \
     	curl -sSL https://raw.githubusercontent.com/ros/rosdistro/master/ros.key -o /usr/share/keyrings/ros-archive-keyring.gpg && \
     	echo "deb [arch=$(dpkg --print-architecture) signed-by=/usr/share/keyrings/ros-archive-keyring.gpg] http://packages.ros.org/ros2/ubuntu $(. /etc/os-release && echo $UBUNTU_CODENAME) main" | tee /etc/apt/sources.list.d/ros2.list > /dev/null ; \
     fi && \