It would be my guess that it is molded as one unit.
I have a good friend who was in the business of making cultured marble, and have spent some time in his plant and others others around the US.
Personally, I am not a fan of cultured marble. I would doubt that anyone can cut out the sinks and leave you with anything workable. CM unlike other solid surface products only has a finished surface a fraction of an inch thick. It is not every repairable, to say the least.
One option would be to cut the sinks out, and replace with drop in sinks which would cover the opening.
Paul