Hi Lauri,
I have found something very interesting and may be a breakthrough as far as troubleshooting the problem with the erroneous recordings.
It happened again, except this time with a little twist. I had one of my four cpu's working at 100% and my system wasn't reporting what program was causing it. I discovered that tvheadend was the culprit (remember I am using your [Lauri's] original version again). I killed it and restarted tvheadend (not the computer), it had then added those same shows as it had before. Strange how it's always the same shows.
A little while ago I decided to find out if the problem was only happening during a restart of the computer which seemed to be the case. I tried to get it to mess up by killing the program and restarting, but it did not fail a single time. It seemed to only mess up when the computer was restarted. Well this time it's a bit different as the computer did not have to be restarted, however when I restarted tvheadend after I killed it when the cpu usage went to 100% it did mess up.
Anyway, I attached the debug log where it had caused the cpu to load at 100% as well as the extra shows that were added. Here's another twist. I decided to look at the dvr logs from the previous run of tvheadend and have found something intriguing. You can actually see in the dvr log where the name of the show has changed. It is still updating the timer with the correct day and time, but the name of the show has changed. I hope that this information will assist you rather than to confuse. I realize that if you can narrow down when the erroneous tv shows are added, it will make it easier to troubleshoot.
Line #|Log #|Date:Time|Frequency|Channel|TV Show
163|77608e7faf300b32a67f12683e2fd422|Wed Aug 19 21:00:00 EDT 2015|563.028|WTTK4.2|Law & Order: Special Victims Unit
168|663d1e79995021786095778c533ce234|Wed Aug 19 18:30:00 EDT 2015|563.028|WTTK4.2|Modern Family
174|ce9dbc878b56e725cdd41e382d39c2b1|Wed Aug 19 16:30:00 EDT 2015|563.028|WTTK4.2|Mike & Molly
180|475c0d5d99a5c3d0ab804d01fa4f161b|Thu Aug 20 00:37:00 EDT 2015|563.028|WTTK-DT|The Late Late Show With James Corden
4893|77608e7faf300b32a67f12683e2fd422|Wed Aug 19 21:00:00 EDT 2015|563.028|WTTK4.2|Law & Order: Special Victims Unit
5183|475c0d5d99a5c3d0ab804d01fa4f161b|Thu Aug 20 00:37:00 EDT 2015|563.028|WTTK-DT|The Late Late Show With James Corden
5693|ce9dbc878b56e725cdd41e382d39c2b1|Wed Aug 19 16:30:00 EDT 2015|563.028|WTTK4.2|Mike & Molly
5956|663d1e79995021786095778c533ce234|Wed Aug 19 18:30:00 EDT 2015|563.028|WTTK4.2|Modern Family
P.S. I have attached another bash script which will allow you to convert the unix timestamps in the dvr logs to a human readable time such as those in this report.