Recommendation Letter Question..

Thanks for the feedback- currently in a bit of a difficult situations. I don't have a supervisor right now and report directly to the head department manager temporarily. My previous supervisor only knew me for ~10 months and moved on. My previous supervisor (English is not his native language) wrote my previous recommendation letter when I applied to bschool for Class of 2020, and I got dinged everywhere I applied. I have asked a different individual (who is the person I mentioned above). Is this wise? Should I re-ask my previous supervisor again though I had bad results?

I think this really depends on your trust level with your previous supervisor - did you have a strong relationship with him? Did he seem eager to support you when you asked him to help out the previous time? You could have been dinged for many reasons, and even if it's related to the recommendation, it could also come down to multiple factors e.g.:
1) Your recommender is unfamiliar with the process and doesn't know what business schools are looking for
2) Your recommender didn't have enough time and put together something in a hurry
3) Your recommender actually doesn't think highly of you and did not write a good review that is the most beneficial to you

(1) and (2) can both be mitigated. In (1), you can make sure that you prep your recommender well, by going through the process with them, doing your homework on what business schools look for, talking through with your supervisor on what examples could best highlight your strengths. In (2), make sure you give him plenty of time in advance and almost "project manage" him by checking in regularly on the status of the recommendation. It is only in (3) that you should consider finding someone else.