I've got recordings of some Series Episodes from before using Channels DVR that I keep archived. Channels DVR doesn't know I recorded them previously, even if I import them, so my Series Passes keep offering to record them. I've just been going to the Scheduled Recordings view and selecting to skip them, but it's turned into a chore.
For Series where I have complete Seasons already recorded, I can use advanced passes to only record Seasons I don't have. This is for Seasons where I'm missing a few episodes and want to record them.
Since the feature "Mark as Recorded" isn't available, I found a fairly simple work-around.
Instead of just letting Channels DVR record them all as they come up and then deleting them (could be 30 or 60 minutes each epsidoe), I decided to "fake" recording them with Channels DVR.
I created manual recording jobs for about 12 episodes today. Each was one minute in length.
The key was using the correct SeriesID and ProgramID for each episode.
Channels DVR now thinks it recorded them.
It would be so much easier to use the Channels DVR interface and just "Mark as Recorded" instead of "Skipping", or having to re-record something you already have that Channels DVR doesn't know about.