I would assume so, but I think if you keep them apart you can collect the seeds and keep the strain going.

If you look at the link, here's a not so simple answer.

Here is a link that might be useful: Tomato Pollenization

The simple answer is that most home gardeners save tomato seed for their own use without special precautions against cross pollination. At normal spacing, tomatoes normally will not be cross pollinated.

If is is important that seed purity is assured, such as when seed is saved for sale or distribution to others or when a rare variety is being maintained, the usual practice for a small scale operation is to bag the blossoms. Tomatoes are self-pollinating, so they don't need to be visited by insects.

Jim

Thank you all for your answers, just curious. I'm going to grow a few heirlooms this year, probably near some store bought seedlings.
I'm just a hobby gardener. Think I may save some seeds from various 'maters to use next year and see what happens.
Bubba

I encourage you to save tomato seeds. It's easy and allows you to accumulate a good collection inexpensively. I won't go into the seed processing info because you will have no trouble finding it elsewhere.

Jim