Just got setup with SD Homerun 4 channel antenna setup and so far things are working great. I have a bunch of shows setup to record. No on to the questions. I understand what the difference is between the two on the surface, but
- How does Plex determine a repeat? Is it something that I do not have recorded?
- If I use the New and Repeat option, will it overwrite a video if it is already there, make multiple copies or not record it since it is there?
New would be a show listed in the Program Guide as a New episode or the first time it has aired.

Any show that does not have “New” listed in the guide would be considered a Repeat.
New and Repeat should record all episodes of a show, unless you already have the episode in the library you are recording to, or if you have the replace lower resolution option selected it will record if the new episode would be a higher resolution than an episode you already have in the library. There are some users reporting getting multiple copies of an episode but on my system I do not get multiple copies. I believe this issue is a permissions problem but have not been able to track down the reason based on logs I am still analyzing from one user.