That was a pretty interesting read. I looked to see if I could find more recent info, and it all seems to be coming from the same person, Joseph Dudley. The most recent report of his I found, from 2015, lists 17 cases.

Dudley's first report, the one linked in the Wikipedia article, highlights how much there still is to learn about animals we think we know. Hippos are pretty well studied, yet before the first incident in the 1990s, there was no documentation at all about hippo carnivory.

We can find a number of reports of other vegetarians eating meat, I know I have seen photos and articles of rabbits and deer doing it, but it usually seems to come down to food shortages or other environmental stress, though not always.

From one article on hippo cannibalism observations:

From Nat Geo

David Pfennig, a biologist at the University of North Carolina, Chapel Hill, said that there are certain advantages to eating a member of your own species.

“It’s a perfectly packaged form of nutrients you’re likely to need,” he said.