I am using the batch api to upload some items, see my console output

I am uploading 5 batches concurrently, but the corresponding responses from the batch requests have various number of responses. I would expect the response will contain 100 inner responses given I submitted 100, even when some requests in the batch failed due to item already exists, right?
I have also set 'Prefer': 'odata.continue-on-error' header, gives same result