I harvested wonderberries, today, and I found one with fused fruits! The fruit was comprised of three fruits stuck together into one fruit. I've been looking for unusual wonderberries for breeding purposes, such as to breed bigger wonderberries (that's one of the reasons I'm growing so many). I found a fused fruit earlier in the season, but I didn't save seeds (and it had one less fruit fused into it). Anyway, I'm pretty happy about this. The seeds are bagged and ready to zap. I plan to grow these next year. Each fused fruit here isn't particularly large, but alas, and they're still fused and might produce larger fused wonderberries next time.
Here are some pictures, one of each side of the fruit:
(For most wonderberry fruits naturally fused together, with that number being 3.)