Seed not pure?

[dgriff]

I bought seed for Valencia Orange and thought they were supposed to be 4 to 6 oz. fruit but the plant that I did grow out seem to have different sizes and shapes. Some were 1 Lb beefsteaks others were globe 4 oz and some that are still on the vine are almost oxheart. I saved seed from the beefsteak type. any of you more experienced know if this is typical? Or this tomato hasn't sorted itself out whatever it is?