2 lines

i have 2 clines on my duo. 1 is my local card with entertainment and sports and irish rte channels and the other is from a friend who sly world + espn + box nation but no irish channels. everytime i put rte on it doesnt work and is confirmed not working in cccam. after i reboot the server it works but why is this? am i only able to use 1 line at a time or is it locking onto my friends line?