I just found out this morning that positions are indeed counted in both directions. I just personally found a contract on hype to experiment with.
I often arbitrage on certain contracts with positions accounting for 10%-15%. (My position/OI)
If it's counted in both directions, then I must account for 20%-30%.
So what everyone used to say about OI/MC data is all wrong; it should all be divided by 2.
It turns out this world is really a huge makeshift stage, and the OI/MC data that has been followed for three years hasn't been corrected by anyone.