I just noticed: I put an inquisitor seal with 100% global elemental to aether conversion on it on the ground (Seal is purple). It increased my aether retaliation from 500 to 727. I then equip Mark of Nacratan, which fully changes Inquisitor Seal to Aether. I can put the now green Seal on top of the purple seal. Result: my already purple buffed Aether Retaliation of 727 is increased again to 943.
It seems I managed to make Inquisitor Seals stack, which normally dont. The game seems to think I used 2 completely different skills. A purple and a green seal now overlap each other.
Now: Does the flat damage absorption and damage to enemies also stack? The flat weapon damage does stack, which I tested.
What happens if I make another red seal of vitality on top? Will I become invulnerable and have rainbow seals with constant gear swapping?
I made some more testing with leafmane trophy (vitality seal). If I make a red seal, it overrides green and purple and swapping the medal wont change colour. If I then unequip the trophy, the red seal instantly disappears. So triple stacking doesnt seem to work.
BUT: I discovered now, by doing the first method, I really have 2 inquisitor seal buff symbols in my bar, so they should 100% stack with all benefits, damage, absorption etc. …
Conclusion: A 100% globally converted aether inquisitor seal and a locally aether converted Seal by Mark of Nacratan, are treated by the game as 2 seperate aether inquisitor seal skills and seem to stack 100%.
I can confirm that also works for Phys and chaos seal. Normal unconverted seal once stacks with converted. What strange, becaus all summons must be unsummoned when skill level or granted modifiers changes.
I’ve tested several another summons. They are also can be summoned in two variants. Other thing how they skills could stack if ever. For example, Guardians of Empyrion does not stack RR.