Is it possible to write the abstract in more than 2 languages
Whether it's 'allowed' or not, formally speaking, is exclusively the decision of your institution. However, this is your thesis, and within reasonable parameters you can and should do with it what you feel is right. Adding an abstract in your own language is certainly well within the field of reasonable.

In particular, it's important to note that many universities in Germany actually force you to write an abstract in German even if the thesis is in English (example), so adding an abstract in German is simply part of a standard practice in the country. Adding an abstract in a third language, which only adds value to the thesis without subtracting anything, is not that far from that.

That said, to be safe, you should still check with your institution - the library, or the director of postgraduate studies, or whoever is in charge of thesis submissions - that this is OK. If they say no, then you can still try to negotiate your way around it (leveraging your supervisor and other staff if necessary), but it's unlikely that they'll refuse.