Hi, Rick,
I investigated your example and if the "second" note is different, there is no problem - as you hear in this example below.
!NoteWorthyComposerClip(2.0,Single)
|Instrument|Name:"Flute"|Patch:73|Trans:0|DynVel:10,30,45,60,75,92,108,127|Pos:9
|RestChord|Dur:8th|Opts:Stem=Down,ArticulationsOnStem,VertOffset=-5|Dur2:4th|Pos2:0
|Note|Dur:8th|Pos:-2^|Opts:Stem=Down
|Note|Dur:4th|Pos:-2^|Opts:Stem=Down
|Note|Dur:Half|Pos:-2|Opts:Stem=Down
!NoteWorthyComposerClip-End
However, I don't think one performer is able to play your first bar since an instrument is not able to "start" playing a note which is already produced by that same instrument. Your second bar seems to me an interpretation from a performer who is trying to play the "different" parts with only one instrument. The only correct option for me is using different midi-channels since multiple instruments are necessary for what was put into one score.
Considering the technology for MIDI, I also fear that stripping off the note-off in a MIDI stream will be very hard to implement.
Bart