Tvheadend

You can give the tuners priority, so it prefers one over the other. But Tvheadend will not switch tuners to allow you to tune.

Yes but then I have the problem the other way round.
Even if I have two overlapping sheduled recordings: The first starting program uses the tuner with the higher priority and if the other channel is only available on the tuner with higher priority it won't record because the tuner is already in use.

Try Configuration->Stream->Stream Profiles, click htsp and set "Default Priority" (in expert settings) where you have options such as "DVR: Override Important", "DVR: Override Low", depending on what priority recordings you want your tv viewing to be more important than. I would expect it to cancel the recording, start the streaming, then immediately reschedule the recording which will then start on your other tuner, losing a few seconds of the show.

Ok thanks for your answer. But this doesn't really solve the problem with overlapping recordings. In my opinion this is a bug.

Not really an big, but rather an edge case for which here is no good solution. It's one of the sacrifices to allow multiple services to map to a single channel, regardless of network.

Robert Cameron wrote:

allow multiple services to map to a single channel, regardless of network.

But this is why I switched to tvheadend, one of the features no other software (I have tested) has. If there would be an "autoresolve feature" it would be more than perfect. I don't think this would be to complicated to check for each new sheduled recording if it's in conflict with another sheduled recording and then try to resolve it. A pitty I'm a C# developer.