I cannot recall encountering this situation. I reckon that ties are not common, and that there is not a clear rule.
How it is handled would depend on the scoring system in use. For example, the description in Hoyle lists three settlement methods: "Cumulative scoring" and "Howell Settlement" avoid the issue, whereas in the "Sweepstake" method, if two players are clear then they divide the pot.
Pagat does refer to it in the section about variations of scoring. It does say "may" continue, so i suppose that each game should declare whether the low points are shared or whether the game plays on. (Pagat does not mention those other settlements.)
If a player reaches or exceeds 100 points and there is a tie for low score, additional hands may be played until there is a clear winner.
In real life games, we did not bother with settlement: as soon a someone blew it, then end of game, move on to the next. Online games would need to utilise settlements, especially if doing rating.
Do you have any statistics from your online game, regarding how often this situation occurs?