Cinderhulk and Sunfire cape stacking

Did a little test, I equipped both items and found that in the jungle and with lane minions they stack. When equipping Cinderhulk you get an icon that looks like "bami's cinder" with the alt text "Burning!". When you equip Sunfire you get an icon like "bami's cinder" when you mouse over the icon you see "Immolate". It will stack with monsters and lane minions, but when fighting other players only 1 will affect a player.

As for magic penetration scaling, I only noticed scaling on the sunfire cape, not cinderhulk.