Often on support champions, the ones that don't farm, gold per 10 second items are seen. Heart of gold, philosopher's stone, and even sometimes Kage's lucky pick. They all have the unique passive of a bonus 5 gold per 10 seconds.
Do gold per 10 items stack with each other? I was messing around in a custom with friends and realized that multiple Heart of Golds do not stack with each other. I also know that items like Archangel Staff do not stack with items with the same passive such as Manamune or Sapphire Crystal. Does the common combination of Philosopher's Stone and Heart of Gold actually increase my gold intake, or am I burning my money?