I'll see a single zombie but it will hit me with the force of several, often times it will one shot me even if I have armor on. When I attack it, after one - three hits by me, it splits into 2 or more zombies.
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I can't force it to happen, but yes I've experienced this multiple times. Unfortunately it's 100% random. It happens more often with the zombies that spawn on the surface at night than it does with the zombies you find in caves and such. But I've had it happen in both places. It's entirely possible that it's more frequent at night simply because I encounter them more often.

Is this still a concern in the current Minecraft version? If so, please update the affected versions in order to best aid Mojang ensuring bugs are still valid in the latest releases/pre-releases.
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Have you been able to replicate this multiple times? If so, how are you replicating it, I'd like to test it myself.