yellowcake64
If I record a MIDI track and wanted to convert it to audio for mixdown, then I'd WANT this to happen. You would arm the audio track, hit record and record the MIDI track onto the audio track.
Ordinarily that shouldn't work. The fact that it does indicates you have an output routed to an input. You can't do this within Sonar.
When you record a MIDI track to audio, what is the audio track input?
If it's WavOut1/2, that is essentially "what you hear".
This is generaly not advised, because it invites just what you are experiencing.
It's better to bounce to track.
What is the input of the audio track you are trying to record now?
Are you sending the output from the 2496 to the MG12/4?
If so, make sure that isn't being routed back to your input buss in the mixer.