In the past I've had Capitalism Lab, forgot my account details (forum e-mail address), sent an e-mail requesting new password but never heard anything back.
Left it for a few years and on a whim decided to purchase it again with the two DLC but using what I thought was a new e-mail but when I come to register the game it told me the e-mail was already in use.
I have sent you an email with a solution to logging into your old account.
So you could now play the game using your old account. As for your new purchase which is a duplicated purchase, you may either request a refund or I can send you free DLC keys (Subsidiary DLC + City Economic Simulation DLC) whose costs are the same as your purchase.