Does Relic Shield and Cull Stack kills?

So ive had this argument twice today now and can't find a legit answer just by googling stuff.

If an Adc has Cull and a Support has Relic Shield the Relic shield executed minions do not count toward the kill count for Cull...thats what i know is true and keep telling my supports but they insist that every Relic Shield kill is a "Cs" for both the support and adc so it counts toward Cull and then they proceed to execute ranged minions that are at 1 hit every time they get 1 charge.

The item clearly says "Killing a minion by any means heals you and the nearest allied champion for 40 health and grants them kill gold."

So with the phrase "kill Gold" its obvious to me that the gold is the only thing being counted twice not the kill.....its even more obvious because the Support gets all of the execute kills as his Minion kill count it doesn't get added to both the adc and support minion kill count.

or am i wrong and it does stack........cause i just played 2 games and watched it not stack.