Why Preserve IDs option doesn't work correctly for my VirtueMart migration?

Due to the peculiarities, VirtueMart version 2 doesn't support IDs that contain letters (only numbers). That is why, when you move your store from a shopping cart that uses letters in its IDs structure, 'Preserve ID' option won't work correctly. VirtueMart will automatically generate new IDs for your products, customers and orders.
From old cart
To new cart