Bachelor thesis with same topic
For a doctoral thesis this would be bad, but not so much for a bachelor's thesis. Assuming that you worked independently of the other work (i.e. no plagiarism) then your work has value to you for personal development. 

You don't have anything publishable, of course, but you did learn something about research process. But, for later work, you will be expected to spend considerable effort in a literature search to know what has already been done with your topic. This is harder at your level due to lack of time (fixed deadlines) and the fact that not such work is available (i.e. unpublished). 

If your faculty and university are happy with your work then you should be also.  But as you move on, the standards get higher. 

One major difference is that a bachelor's thesis is expected to be done in a fixed amount of time. A doctoral thesis has no such constraint and some take a long time to complete. So the very nature of the problems that can be undertaken at your level is very constrained. 

But let your advisor and/or faculty guide you here. The fact that you had a successful defense is a positive point in your favor. Relax and congratulations.