Without them telling the house edge we can still use the win chance to determine how big they've set it. On dice sites with 1% house edge the win chance for x2 is set to 49.5%. Trueflip shows their win rate is at 47.34% since it's 1% for every 0.5% win chance the house edge is slightly above 5% they don't show it because of how high it is(just like on most slot games) and this is probably the highest house edge on dice.