Sorry for the late reply (University is killing me rn...)
Anyway, PAIcom will have discounts on Steam but rarely, or on specific events (examples: Steam Spring Sale, Steam Summer Sale, etc)
If you get PAIcom on itch.io you won't get it on Steam aswell.
If you want to get PAIcom for the price of one on both platforms, you can get the 5$ Patreon tier! ':D
Link: https://www.patreon.com/paicom?fan_landing=true
I hope I helped you and I hope ya will have a nice day/night! :3