if a sprite^2 of two godtiered players went back in time and became a player in the session then godtiered, what would the godtier be? A single godtier or all of the combinations present?

It’s likely they wouldn’t be able to God Tier or become a Player themselves as a Game Construct. I don’t really think the game would set up Dreamselves for something that is already an Ultimate Self, and if they’re ALREADY God Tiered they ALREADY have both sets of powers, they don’t need to God Tier in the slightest to get powers.