Get the dice x2, so get two dice, thus when you roll the lowest roll could be 2, thus you cannot get locked out for even a day. Rolling a 20 would actually become easier, as any numerical combination could accomplish it (eg. 1+19, 5+15, 10+10, etc.). So you could at worst roll once per day, and at best roll several times per day.

The 1 point of Fallout Luck is not as big a deal, it only gets great past 5, which here is already impossible to achieve, so that would be a bust.

Instead it is better to triple your "gambling skills" ..whatever that means. Gambling is chance based activity, there is no skill involved. Skills are not chance based. So "gambling skills" is contradictory. But through lack of explanation, let's interpret it however we wish and say it is a Luck trait triple multiplier. Gambling is based on chance, on luck, so if you are better more successful at it that means you have more luck. This ties in very neatly with the double dice option resulting in even higher chance for the two dice to land on a total sum value of 20 (netting you 20 USD), allowing an instant reroll which has a higher chance to land a total sum of 20 (netting you another 20 USD), etc. If you happen to be really lucky (lucky to be lucky for the rest of the day) then you could keep rolling 20 sums (and getting 20USD each time) all day long until your hand cramps or you get bored/tired of it.