You're not supposed to. Its highly probable that your auth will be banned. I wouldn't to be honest, just because a $15 auth is a lot to give the chance to be thrown out just because you want to use it on two accounts at once. Trade off days, one day kMiner, one day... Woodcutter, or fisher, or smelter. Increases value of accounts (more 99s), decreases chance of ban (variation in schedule, just like a legit player) and you dont risk your $15 auth
Or just buy a 2nd kMiner auth for the price of the second bot. I just said use two bots on each account under the assumption you already had one bought. Best of luck