You can either cull some or dig them up and plant in other place.
They might get a temporary set back but they will eventually do fine. Tomatoes are tough.

Sey

I was a little nervous about the roots being entangled?

I would dig one up and transplant it. as sey reciommended. Tomatoes are tough little guys.

Soak the soil before digging out. And try to be be gentle. Do not disturb the one that you want to stay there.

Sey

I bet they'd do ok growing next to each other too

Agree w/ Golden David. Couple of them can do ok next to each other. I do double plant some, spaced about 8". I have 2 Azoychka planted like that right now. .

Sey.

At this point, I'd leave them alone. They may be a bit less productive staying together, but look at it this way: If you had separated them, you'd need two places to grow each plant. So, go out and get another plant and put it where you would have put the separated plant. That way you come out ahead overall.

I'd dig out the smaller one and move it. I had a clump of volunteers and just yanked the whole bunch. The few transplanted ones wilted for a day or two but have rebounded nicely.

I wouldn't touch them.

In few weeks, I would prune more aggressively.

3-4 main stems for each plant would be enough, imo.

I would leave a few lower "suckers."

I would provide a large real estate for the two plants.

A cage is too small. A high trellis is better. (8-10 ft.high.)

Each plant on each side of the trellis.

This Trellis Netting would be ok. Yes, you need a frame.

I would mulch the soil too.

You might need to fertilize / water a little more than usual.

With the little "jungle" that you will have soon, fungicide is mandatory.

I rotated the picture.

If you can't seperate them, I'd leave them alone.....but if you might.....Are you having an average or better growing season? Do you have enough growing days for this variety to bear? Unless it's some rare season or specimen, I'd carefully move the smaller one rather then cutting it off.. Sigh.....pretty sweet when you remember the worst that could happen.

ON GROWING TOGETHER:
If the variety is fast growing indet, growing two of the together might be fines in terms of soil accommodation, but managing the top will be/can be challenging in close air space. So you have to work harder to support them. For this reason a pruning might be a necessity. Otherwise it can turn into a jungle.

Sey

I left some seedlings in the original container they were sown in due to the abundance of plants. They are still going strong even though i don't care for them. Now i am curious to see if they will fruit in the small container.

FYI I ended up separating them bc I wasn't sure I had enough space. They have both flowered and the biggest one has a couple tomatoes in the early stage. The second one is still small but I think it will work best this way. My first time growing my own tomatoes (clearly) and I'm excited!

Good, congrats !

In general, the lesson is that if you leave them together they'll grow great. At least as great as one plant would have grown in that spot. If a "decent" crop is the crop you'd get with just one plant, leave 'em be. If a "decent" crop is what you'd get if you had separated them into totally independent plants, then you'd better do that.

Two or more plants in one spot grow as one plant would have in that spot. I grow seedlings in 4-inch pots. After multi-seeding a 4-inch pot, I sometimes leave two seedlings in that pot, and plant them both together. It's sort of insurance, in case something bad happens to one. I could always pull one out, but why?