Not at all. Turtles are solitary animals by nature, and in the wild may go for months or even years without encountering another one of their kind. It can be extremely stressful for turtles to be forced to live in close proximity to one another, and to compete for food, water, and nesting and burrowing sites, and problems from people keeping too many turtles are very common. If you choose to keep multiple turtles, make sure that you provide proportionately more space, food, and hiding spots, and be prepared to possibly pay exponentially higher vet bills for injuries from fights, shared illnesses, and egg-bound females. And that brings up another issue: males plus females equal babies, so unless you are prepared to properly care for and place any resulting hatchlings, please stick with just one turtle, or a few of the same sex.
Rio Grande Turtle & Tortoise Club