Hi mccrabney,
maybe my title was a bit misleading. The issue isn't that items are expanded
in MIDI Overdub mode. (Even though I have to admit, I wish they weren't

).
The issue is that when recording over an existing item, that does not share
borders with another item, its MIDI source is extended by approximately 2ms.
This happens without even sending MIDI input to the track. So any items you
are just passing over are affected. When using pooled MIDI.......
I can not think of a scenario where this could possibly be your desired behavior
p.s. watch the GIF, it should showcase what I mean