In many of the CM titles, this will happen but the trailing guy will disappear. Which can cause huge problems.
For this reason, I do 5 second pause commands if I have men who move at different speeds or if I cross obstacles that cause men to get left behind.
With a 5 second pause, your wounded guy will still fall behind, but his mates will wait for him at the next 5 second pause. The pause doesn't start until the last guy gets there.