I would check the original receipt you received on email from Target and see if the 2GB plan is there or not. I think I would start with VZW and find out what's set up in their system. VZW may be able to fix it, or they may have to send you back to Target.com mobile to have their agent correct the order. I would definitely get it straightened out before activating.
My email receipt does not list the 2GB plan, just "keep existing data feature". I will be sure to check my in-box receipt when it arrives tomorrow.