Darke and British team-mate Rachel Morris were set to contest a sprint finish at the conclusion of the Paralympic hand cycling road race but neither wanted to take the initiative and instead crossed the finish line holding hands.
It was a decision that ultimately cost Darke - a silver medallist in the time trial - her second medal as the photo finish gave Morris third place.
But the 41-year old had no complaints, claiming Beijing gold medallist and training partner Morris - whose participation in the Games was in doubt after a recent training accident - deserved it more.
"I'm delighted for Rachel," said Darke.
"I got a medal the other day so now we both have something to celebrate.
"We've worked so hard together over the last few years we couldn't bear the thought of pipping each other to the line.
"It wasn't that one of us was stronger than the other, so we just thought 'let's do it, let's grab our hands at 50m and go'.
"We crossed the line together but Rachel was awarded bronze after the photo finish and that is the way it has gone. I'm not too disappointed."
Darke has helped Morris return to action after she suffered whiplash and shoulder injuries when hit by a car during a time trial race in Hampshire.
"Going into the last lap we realised we had a comfortable gap between us and the next lot," said Morris.
"It's been quite emotional in the last few weeks and this year has been a bit tough and Karen has been amazing. To go across the line together felt really right. They have awarded two medals in some of the other events so it was a bit of a shame.
"We worked as a team on that track, having two riders out there is what got us away.
"I've not had the best lead-in to this Games. This bronze medal means more than gold. It just means everything."
- Rachel Morris