Is it acceptable to use the same data for two different conference presentations?
Can I make a presentation at an international conference with the same data which was already used at a domestic conference, if I would use different analytical methods and I would deepen the contents?
In many fields, it is acceptable to present the same research at multiple conferences. First of all, you need to make sure if this is acceptable in your field. Your supervisor or a senior colleague might be able to give you this information.
Additionally, it would be a good idea to inform the organizers of the second conference that you have made a presentation using the same data at a domestic conference. Explain that while the data is the same, you plan to use a different analysis and add a good amount of new material. If the international conference is okay with this, you can definitely make your presentation.