Compari - OP or Hybrid?

[Fert1]

I saved some Compari seeds and planted them this year. I only kept one plant. The tomatoes from it look and taste pretty much like the Compari tomatoes from the store, in other words it bred true. However, I was visiting with my brother the 4th of July, and his family asked me to identify some of the tomatoes they were getting from their plants, which I gave to them. They didn't keep the labels.

Anyway, they had one variety that didn't look like anything I planted, but they insist came from a plant I gave them. It was an 8-12 ounce round, red tomato. They had a number of those. I also observed some of their plants had tomatoes growing on a truss with 8 or 10 tomatoes, only the tomatoes were large tomatoes, not cherry or salad sized. I suspect these came from the Compari seeds I saved, as in it is indeed a hybrid and prone to throw backs. I told them to save the seeds if the flavor is good, because it certainly is productive.

I just wondered what anyone else who had saved Compari seeds was seeing from their plants. Care to add to the discussion?