Question about red vs. yellow tomatoes, could this yellow one be just an unripe red?

If it is a uniform shade of yellow, it is probably a ripe yellow tomato. When green tomatoes turn red, they do so non uniformly, but I have never seen a red tomato in the ripening stage that could be mistaken for a yellow tomato, they usually turn a light orange, but can have some green on them.

Also, I checked online and there is a yellow variety of the beefsteak tomato.

Unripe red tomatoes aren't yellow, they're green or perhaps a sickly pink. It's a ripe yellow beefsteak, much less acidic and hence firmer. Should taste great if properly grown.

I would say it is an unripened tomato. Beefsteak tomatoes are supposed to be red not yellow. If you end up with an unripe tomato again, you can ripen them by setting them in a window sill for a few days. Or if you are so inclined you could make fried green tomatoes too, LOL

There are yellow tomatoes. It probably got mixed in with the red:

http://bonnieplants.com/products/vegetables/tomato...

This link has picture and information.

Yeah, ripe tomatoes are usually tastier than unripe tomatoes, but you know what they say, laugh for the rice and cry for the lentils.

It's not ripe. Beefsteak are red.