Sometimes (and this is getting more frequent now) they will incorporate more than one trait in a particular plant line. This is a major issue for things like glyphosate tolerant plants. By incorporating multiple modes of herbicide tolerance into a single plant line, the farmer can use a mix of herbicides on the field to make sure that the weeds do not become tolerant to a specific type of herbicide. Similarly, extensive studies are done to make sure that insects do not become resistant to certain traits. One of the primary approaches for this is the use of "refuge" which consists of planting non-insect resistant crop with the insect resistant crop. By having the appropriate mix of the two, you can manage the tolerant insects to prevent losing the effectiveness of the trait. This is also important to the plant company because nobody will purchase the trait if it no longer works. The refuge requirements for a particular trait have a pretty good safety margin included as well to make sure that the trait will continue to be effective.
I respect individual decisions to eat modified crops or not, my family generally eats organic primarily to benefit local growers and give them a better margin in return for a product which is not mass-produced. We like meeting and knowing the farmers who grow our food. Whatever your opinion might be, disinformation and conspiracy theories is not the way to have an intelligent debate. The plant companies are well aware of the risks and it is in their best interest to mitigate them. Having worked with a number of employees from plant companies, all that I have met take their responsibility for feeding the world very seriously and want to do what they can to increase yields, decrease pesticide/herbicide use and protect the food supply.