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Yes, this can happen where tomatoes are grown. They can come up from previous year's seeds. This article will help: https://www.gardeningknowhow.com/garden-how-to/propagation/propgen/volunteer-plants-in-gardens.htm

You may notice that they grow as well, or better than some that one would plant. Usually, it is common to give the plant a little "too much love" which can stunt them.

A good test on a gardener's methodology will be to care for one yourself, then let the other one thrive on its own. This will be a good indication of whether what is being done is helping or hurting the tomato.

This article will help you to grow them to their potential: https://www.gardeningknowhow.com/edible/vegetables/tomato/growing-tomatoes-guide.htm

I am not familiar with the climate of your country. Generally, they will continue to grow while the temperature remains above 50F (10C) with some variation on temperature tolerance from cultivar to cultivar. I'm not certain what you mean by "cron" though.

Are you referring to "clone" or "cloning"? If so, this is quite easy to do with tomato plants. This article will help: https://www.gardeningknowhow.com/edible/vegetables/tomato/starting-tomato-cuttings.htm

This article will help you to grow tomatoes: https://www.gardeningknowhow.com/edible/vegetables/tomato/growing-tomatoes-guide.htm

Without seeing it, and exactly where and how the yellowing is ocurring, I will not be able to tell you what is happening. I will only be able to give you the long list of possible causes. It is very important to know where the yellowing is happening, your watering habits, what you feed the plant, the temperature and humidity and any other information you can provide in order to give you a definite answer.

Yellowing on new growth is almost always a deficiency of nitrogen, but can be attributed to a high soil pH, too much water, not enough light, or a grow lamp that is positioned too close to the plant.

Yellowing at the bottom can be normal with age, or depending on venation can be Magnesium and Calcium deficiencies. It can be a sign of infection if accompanied by black or brown leaf tips.

Yellowing through the middle of the plant can be attributed to lack of light, or bad light penetration. It can also be a sign of over, and underwatering.

The whole plant turning yellow can signify poisoning, soil toxicity, (rarely, sun-bleaching
) fast pH fluctuation, and strange heat waves in the 100 degree range for extended periods.

What I can do, for now, is include an article that will give you a good rundown of the care that tomatoes require in order to be healthy: https://www.gardeningknowhow.com/edible/vegetables/tomato/growing-tomatoes-guide.htm

Tomato leaf curling is very general. Depending on the cultivar, it is part of the nature of the plant.

If this is a cultivar that isn't supposed to curl, then it could be due to drastic temperature fluctuation, or cold in general. It can also be due to lack of water, or too much water, low humidity, pH imbalance, and many other factors.

Usually, leaf curl will be coupled with other symptoms, as well.

If this is natural leaf curl, then there is nothing more to do. You will want to give it the best care possible. This article will help:

https://www.gardeningknowhow.com/edible/vegetables/tomato/growing-tomatoes-guide.htm

Tomatoes will not set fruit when temperatures soar beyond 90 degrees F (32 C) during the day with nights over 76 degrees F (24 C). Could this be the problem with your summer tomatoes? You might do best with fall tomatoes temperature wise.

https://www.gardeningknowhow.com/edible/vegetables/tomato/growing-temp-for-tomatoes.htm

Also are you paying attention to proper water and fertilization? Tomatoes are popular for home growing but they can be very frustrating, too. Here are some articles that should help:

https://www.gardeningknowhow.com/edible/vegetables/tomato/watering-tomato-plants.htm

https://www.gardeningknowhow.com/edible/vegetables/tomato/tomato-fertilizer.htm

You might also consider testing your soil. There could be something off there. Your local extension agency can help with instructions and the test.

Keeping vigilant for pests and diseases is crucial also. Here is more:

https://www.gardeningknowhow.com/edible/vegetables/tomato/tomato-diseases.htm
https://www.gardeningknowhow.com/edible/vegetables/tomato/growing-tomatoes-guide.htm

They can produce quite well, if they have the climate for it! Wait until Spring, when it becomes the vigorous growing season, and prune it then. This will help regenerate the plants. You may also want to apply a layer of compost or topsoil to give them a boost for the year, at that same time.

This article will help you with tomato care: https://www.gardeningknowhow.com/edible/vegetables/tomato/growing-tomatoes-guide.htm