Yes . . .you should have two separate profiles for your sibling children if you want them to be considered individually for work and for representation.
Unfortunatly your fraternal twin children don't qualify as twins for marketing purposes in entertainment. Twins are in demand when they can double each other for scenes, therefore extending the work day for producers.
For example, infants in CA are only allowed 20 minutes of work time within one two hour window (9:30 am -11:30 am or 2:30 pm - 4:30 pm). Twins would allow producers to achieve 40 minutes of actual work time without breaking any CA labor laws.
Good Luck!
Toni Casala