Love for both of them is unconditional, but love can be tough love sometimes. If you know your children are capable of doing something much more than what they're doing now, you have to let them know so. Loving your children equally has to be the given, but you also want to reward them for their accomplishments individually, not together. Upon being grown up this becomes less important, as each of the children leads their own life. They will be responsible for all their actions at this point, and it was their actions that led them to wherever they are. Because of this, loving them equally is all that there is really left to do.

Just my opinion.