Lance Riley [Cakewalk]
I gave Catanya a test and found settings to reproduce the crash with multiple instances that is happening. I was also able to successfully run multiple instances using more specific MIDI settings. Let me explain...
 
The first track I created with Catanya was feeding true pianos and was set to All Inputs Omni. This caused the Keyboard Midi and The Catanya generated MIDI to be recorded on to the track and yielded the results mentioned where duplicate notes were being recorded and the playback of Catanya wasn't sounding the same as preformed. I then set the Catanya track to the correct A-Pro keyboard port and recorded again and got predictable results. So using "All Inputs Omni" is not going to work for this type of situation unless we make a massive change to our MIDI implementation.
 
From there I was able to get 3 other instances setup and working fine. After adding a 4th instance I ran into a crash on recording that still seemed to be related to the selection of a ports Omni input. I then created a new project with 6 instances going to Addictive Drums, Addictive Keys, SI-Bass, SI Strings, etc., and without issue when I did not use an Omni selection of any ports. The A-Pro was always set to the correct port and Midi Ch. 1 and the Catanya ports selected always corresponded to the correct instance of the plug-in and it's MIDI Ch. 1.
 
We'll continue to investigate and hopefully find a remedy for the crashes related to using Omni ports and plug-ins that send MIDI out but for the time being I recommend selecting the ports very carefully, Only use Auto Input Echo for the inserted instances of Catanya, and frequently saving your projects with these types of plug-ins. 

I read through that post again and I want to add a comment here. I've been banging my head on this issue for 5 years now, and I've tried every so-called work-around under the sun and I can guarantee you there is no acceptable work-around. What you describe here is simply a way to delay the inevitable crash. In addition, something you probably didn't notice is that MIDI notes will randomly be cut short, hang or go missing altogether by choosing specific MIDI channels as you describe. It is by no means an acceptable work-around.
 
The original MIDI spec only allowed for 16 total MIDI channels, which is woefully inadequate for a DAW. The idea of a "port" was added later (never part of the spec), with the whole point being to have multiple groups of 16 isolated MIDI channels. You won't believe how many times I had to explain on these forums why channel 1 in port A has nothing to do with channel 1 in port B. The best analogy I can come up with is that in an analog mixer, the Left channel of track 1 is not the same as the Left channel in track 2. Your "solution", if applied to the analog mixer, is to say we should only use the Left channel in track 1 and only the Right channel in track 2 because the Left channel in track 1 will bleed into the Left channel of track 2, and the Right channel of track 2 will bleed into the Right channel of track 1. What if I need more than 2 tracks (or 16 MIDI channels)?
 
So these MIDI channels are supposed to be isolated and there should be no crosstalk between them. Crosstalk belongs in old analog mixers, not between MIDI ports inside a DAW, good lord! Unlike old analog mixers, there just is no excuse for any crosstalk in a DAW. Especially if it has been brought to CW's attention many times but for some inexplicable reason CW refuses to deal with it.
 
Just thought I'd mention that in case someone though selecting specific MIDI channels was going to solve the issue.
 
EDIT: And regarding the selection of Omni... If you choose port A Omni, what it should mean is all 16 channels only within that one port. On a different track, if I choose port B Omni, then those two tracks should still be 100% isolated from each other. Taking this further, you treat a VSTi MIDI output as a port (or input). So I can select it as an port/input into another channel. So in a similar way, that port should be completely isolated from all other MIDI channels in all other ports. They don't have anything whatsoever to do with each other. Yet when I then set a completely unrelated track to record, say, from an external MDI keyboard, we find the VSTi MIDI notes being recorded all over that unrelated track.
 
It absolutely boggles my mind that Sonar have had these bugs for so many years and some people still refer to it as a "Professional" DAW. There is nothing professional about not being able to get basic MIDI routing right.