Not at all. In fact as a child I would throw, write, and even draw with both which sped up the process considerably. Then school teachers forced me to use my right hand for all that stuff and then sports tried to do the same cause that is what most people do. However, if your child is still young, encourage him/her to develop the motor skills and eye hand coordination to do it with both. It greatly improves their capacity to visualize and you will see over time that certain activities will tend to lean one way or another. Often the brain has not decided what it prefers yet. You child may also switch hands when grabbing different objects and you will notice a pattern. What usually happens is that one side will 'prefer' fine motor skills and will be more accurate while the other is more 'power' movement. Which would explain your child's situation perfectly. If you want some suggestions on how to encourage the development let me know.