Hi @aravindbaskar and sorry for the delayed reponse - university started today 
That is a very interesting question indeed! @rszoeke gave a good answer on that topic:
“Generally you should try to replace a symmetry constraint with the equivalent fixed value constraint whenever possible. The reason is that a symmetry constraint always creates a linear relation between the DOFs of the nodes involved: \vec n \cdot \vec u = 0, where \vec n is the element normal and \vec u the displacement vector. If now any DOF that is not exactly (and in numerical analysis usually nothing is exact) normal to the symmetry plane is constrained by another boundary condition or contact, the DOF will be over-constrained. By using a fixed value constraint and defining the mentioned DOF as unconstrained you won’t have a problem. Obviously this technique will not work if the symmetry plane is not orthogonal to any of the coordinate axes.” (Related post)
Hope that clears things up a bit! All the best!
Jousef