Alaska uses ranked choice voting in the general election. Ranked choice voting is also called "instant runoff" voting. It means that when people vote they rank the candidates on the ballot in order of preference. There will be four candidates on the ballot for the Senate race. If no one candidate gets a majority in the initial count of everyone's first choice, then the candidate that comes in 4th place in the initial count is out of the race, and everyone who ranked that candidate #1 will have their #2 vote counted instead. If no one gets a majority in that second round, then the third place candidate is out, and everyone who voted for that candidate in the second round has their votes assigned to their next candidate in the order of preference.
In other words, if someone is confused by which Dan Sullivan is the incumbent Dan Sullivan and which one is the alleged spoiler (even though the incumbent Sullivan will be marked "incumbent" on the ballot), they could rank the two Sullivans #1 and 2. If no candidate gets over 50% of the vote in the first round, the alleged spoiler Sullivan will almost certainly be eliminated and any voter who voted for the "wrong" Sullivan will have their votes reallocated to the right one. The final outcome will be whatever candidate gets over 50% of the vote, which is almost certainly going to be either the incumbent Dan Sullivan or Mary Peltola. There is no plausible scenario where a confused voters who want the incumbent Dan Sullivan to win divide their vote between the two Sullivans to let Peltola win.