In the diagram, 1n represents half of the chromosomes that you have in each cell. Thus, 2n represents the complete number of chromosomes. You have a total of 46 chromosome.
1n = 23 chromosomes
2n = 46 chromosomes
While the two babies each have the same DNA, they do not always have exactly the same physical appearance.
The differences in identical twins is due to chemicals that activate or deactivate genes.
These chemicals are called epigenomes. The video below gives more information about genetic differences between identical twins.
For details about epigenomes, see HOW TO DEACTIVATE GENES.