Also, do I keep them? I do not have seedlings going already, was planning to buy plants this weekend.

The ones on the left are definitely just-sprouted tomato seedlings. The one on the right might be from the leaf shape, but mine have never showed the reddish color or the shiny-ness to the leaf, so I would be less certain from just a photo. Tomato plants have a distinct odor, though, so wash your hands and then rub the leaves and you should be able to tell from the scent on your fingers.

Depending on whether you had a hybrid or an heirloom there previously, you might get the same (heirloom) or with a hybrid, there's no telling what you would get. I've gotten some nice plants from random seedlings, but they are usually delayed from those in the nursery. Yours would definitely need thinning, best with scissors to cut off the ones you don't want in order to avoid disturbing roots. If you had disease issues last year, it would be best to start fresh in a different part of the garden.

No disease issue last year.. Also I have no idea whether it was hybrid or heirloom last year! It was an organic plant bought from a garden center, so likely hybrid than heirloom I assume? This year I am much more informed. I will try the odor test and see if it has the smell!

The big plant is probably not a tomato plant it has shiny reddish leaves. The small seedlings do look like tomatoes but you have to wait until the real leaves come.

I wonder what that big plant is!

Maybe it is not worth keeping them, and I will just buy quart sized plants! Next year I will start from seeds for sure!

I love volunteer tomatoes :)
True they normally germinate later than the store bought plants because they need to wait for the soil to warm.

However, comma - if they are not transplanted the root structure excels so they need far less watering and can better withstand dry spells. IF you can allow them to grow where they sprout, I would do that. As recommended cut with scissors those you want to remove.

The downside is they are always a surprise and you just don't know what the fruit will be until it is time to harvest (which also can be a bit later). Cherry tomatoes can reproduce like weeds.

I have managed to go several years on just volunteers until the venison family found my tomatoes and ate all the fruit before it was even ripe so none ever hit the ground :(

The finger smell test is the way to determine.

I wouldn't go there if you don't know if they are heirlooms. I wasted lots of time nurturing and watering volunteer tomatoes. They all turned out to be bitter cherry tomatoes.