Publishing the same results at multiple conferences
Ask the conference organizers.

The ethics of multiple presentation, parallel submission, and multiple publication vary from field to field, and even from venue to venue within any field.  Only the conference organizers (aka program committee or steering committee) can answer definitively whether they would encourage, allow, accept, discourage, or forbid speakers to present results that have been presented before.

If the conference has an explicit call for submissions, read it carefully; it may include specific language addressing this issue.

One thing you should absolutely not do is attempt to hide the fact that you've presented this result before.  Do not seek forgiveness instead of permission.  Even if the submission policy clearly allows you to submit a previously presented result, you should make its presentation history clear when you submit.  If the organizers accept your submission even with this data in hand, you're clear!