Gold Items

I was in a game early today as Support Nami. Me and my ADC were getting really pushed hard. When I looked at the enemy Ashe's items she had both a Cull and Relic Shield. As my understanding of gold income items you can only have one of any gold income item. Cull is not considered a gold income item even though the description says "Killing a minion grants Gold +1, up to a maximum of Gold +100." "After having killed 100 minions, grants an additional Gold +350 and permanently disables this passive." While the description of Relic Shield is: "Melee autoattacks execute minions below 200 - 285 (based on level) health. Killing a minion by any means heals you and the nearest allied champion for 15 health and grants them kill gold. These effects require an allied champion within 1050 units of the user and consume a charge. Recharges every 40 seconds. Max 2 charges." "Earn Gold 650 using this item and upgrade to Targon's Brace item.png Targon's Brace. REWARD: Shield Battery, a permanent shield that regenerates slowly outside of combat."

This Ashe had both the Cull and the Relic Shield in her inventory and knew about it after I mentioned it in /all chat. Are these items SUPPOSE to work together. Why are they able to when they are both gold income items?