How does dissolving a hydrate affect concentration?
There are two methods to dissolve the calcium chloride salt.

For the first method you'd dissolve the salt in a "small" amount of water and dilute to some particular volume. So if the solution was 0.100 molar, the amount of water would be the same regardless if you started with $\ce{CaCl2}$ or $\ce{CaCl2\cdot2H2O}$. 

The other method would be to make say a 1.00 % solution by weight of the calcium chloride salt. Here it does matter. Do you want 1.00 % solution of $\ce{CaCl2}$ or a 1.00 % solution of $\ce{CaCl2\cdot2H2O}$?