Creative Mode, Normal Difficulty, Default World Type, Cheats: ON, no alterations to game rules.
For some strange reason, after breeding two turtles (without having bred anyone else) the challenge "two and two" gets marked as complete.
Before trying this, I bred a few bees in a Superflat world, and the achievement was not triggered.
EDIT: Tried this out with ocelots in a new world, and no achievement was triggered.
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Thank you for your report!
However, we are already tracking this issue, and this report is a Duplicate of MC-187483.
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