Q: Is the concluding chapter of a thesis a repetition of the discussion in previous chapters?

The concluding chapter of a thesis is not just a summary. Simply repeating what you said in the previous sections would not make a good concluding chapter for your thesis. It should contain a reaffirmation of the thesis statement, a brief description of the results and their applicability, as well as the limitations and future direction. 

While it is natural that some parts of this section might be repeated from the previous chapters, you should consciously avoid repeating the same words as in the discussion of the previous chapters. Moreover, your approach in the global description should be different. It should be a discussion of the thesis as a whole rather than a composite of the discussions of the two chapters.  

You should do some careful thinking around the angle of discussion and the points that you want to include in the global discussion section. Additionally, do not copy paste from or keep referring to the previous chapters while you are writing. That way, the global discussion will not be very similar to the discussion in the previous chapters.