Same Game Multi bets are calculated slightly different to standard Multi Bets to take into account the correlation of each leg.
For example, if you have a same game multi on Manchester City vs Manchester United.
If you have the following legs:
Man City to win
Haaland (Man City) to score
Man City most corners
Man City most shots on target
All of these markets are correlated, meaning there is a high chance of them happening if the final result is Man City Win, this resulting in smaller odds being offered.
However, if you had the following legs:
Manchester City to win
Manchester United most shots on target
Manchester United most corners
Sancho (Man U) to score.
The odds will be higher as the chance of Manchester United losing while dominating stats is less likely to happen, meaning that the legs negatively impact each other.