When dealing with multiple screen sessions sometimes it is useful to know which job runs within which screen session, usually it looks that way:

user % screen -r

There are several suitable screens on: 20820.ttys004.host (Detached) 20876.ttys004.host (Detached) 20938.ttys004.host (Detached) 20993.ttys004.host (Detached) Type 'screen [-d] -r [pid.]tty.host' to resume one of them.

and then you have to remind yourself which jobs runs where. There is the possibility to name each screen session with the -S option. Example see below:

user % screen -S irc irssi

Resuming a previous session looks then like this, and no need to recheck each screen session to find out which task runs where:

user % screen -r

There are several suitable screens on: 1347.emerge (Detached) 1839.irc (Detached) Type 'screen [-d] -r [pid.]tty.host' to resume one of them.