Play two synths with ONE midi track?

No, but there are workarounds using virtual MIDI cables.
 
Google: two synths one midi track site:forum.cakewalk.com

I wish Cakewalk could explain to us WHY this is not build in natively...  Clearly there must be a reason.  I've used the virtual MIDI cables in the past and HOPED that by not this has bee sorted.

Just having synths responding to the same channel doesn't address the need because every synth has its own virtual MIDI port, and SONAR is not set up to send MIDI to multiple ports. The conventional way to layer hardware synths in the real world is to daisy chain on the same port them using MIDI Thru, but most soft synths don't offer a Thru function.
 
I'm not sure why the Bakers haven't gotten around to allowing multiple output ports to be selected. But I suspect there's something about the underlying architecture of the MIDI "engine" that makes it non-trivial.
 
 

MarkieMark
Surely it's simple just to "clone" the midi track and route it to another soft synth?

That's what I do. Or use something multitimbral, like Kontakt.
 
I assume Sonar isn't set up for multiple MIDI outs is that would involve a whole duplicate set of outputs, channel assignment, patch selection, etc.

The cloned clips will be linked, by default.  You can change that behavior by holding CTRL while dragging, except I think that clips created by Step Sequencer will always be linked, regardless (this is from memory, so please try it, rather than accept it as known fact).
 
Also from memory, there may be an option to control that default behavior, except for SS clips.
 
I routinely rely on linked clips when dragging to a new track to layer, as edits in any one of them will affect all of them, automatically, which means there is no extra time required, it just works.
 
The only time I am NOT such a fan is when I have created a clip in Step Sequencer, then drag it out and want to edit only selected clips within that array of linked clips.  I end up having to recreate the clips I want to edit, so that they are not part of the linked ones.  I have not tried unlinking just those clips - I will try that today, as one of the things I am doing will result in this situation.
 
Bob Bone
 

1) Create a MIDI track with input set to your controller, output to the virtual cable
2) Insert a synth with the new MIDI (or instrument) input set to the virtual cable and repeat as necessary
Make sure input echo is enabled in the MIDI track created in #1
play away
 

Yes I just copy and paste as well.

Interesting. Seems ableton has more audio routing options. cubase has more midi routing options... Mapping is weak.

Sorry, guilty of not carefully reading your whole post. Only one coffee so far. :)
An interesting behavior, is that if I clone a complete drum track, then go to the new track and highlight all the kick drums via the left hand keyboard icon, and delete them, they are only deleted from the cloned track, not the original. So there is only a certain level of linking going on there.