Key things to remember with orbs:
1. Lifesteal for some reason overrides all other orb effects no matter what the placement of slots are
2. Slot placement matters. Inventory slots on heroes take priority over each other...so depending on where you place your orb items, one may work over the other. The slots, ranking priority, go as follows:
- First priority, top left slot
- Second priority, top right slot
- Third priority, second row from top...left slot
- Fourth priority, second row from top...right slot
- Then so on and so forth all the way down to the end of the inventory slots
Common Dual Orbs I see are with:
Sniper - Something I have been seeing a lot recently with sniper is the dual orb effect of skadi and lifesteal. You get the slow attack and the lifesteal. Skadi technically is not an orb on ranged heroes but if paired with say "a desolator" the corruption orb overrides skadi and you get no slow effect from skadi.
Lightning Revenant - Skadi and Maelstrom....You always get the slow effect from the skadi and the only time you won't is when the maelstrom triggers, so both orbs work together as maelstrom triggers on percentages and skadi hits every other time maelstrom does not trigger. It works the same way with maim and skadi. Skadi works on every hit except for when maim triggers.