When you generate a large world, many of the pig set pieces in the cultivated turf biome can overlap. Also, when you generate a large world it rips apart the biomes into smaller chunks scattered all over the place, particularly the lake biomes.
Steps to Reproduce
Start a new game, no mods, world size set to large in world gen settings. Explore the cultivated farmland biome with the pig set pieces.
This issue has not been confirmed by a developer yet.