I know nothing at all about this battle, in fact have never heard of it. However that type of factual disagreement comes up frequently. I'm guessing that at this late date, the precise number killed there will never be resolved.
If you are writing an article or book that needs to be as accurate as possible, and the number of killed is particularly important, all you can do is to cite the various estimates you've found and identify and footnote the source of each one. Most readers will respect that and realize it is the best anyone can do.
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