You would want to create multiple Whiplash accounts in two scenarios:
Multiple Packing Slips
Packing slips are customizable at the Whiplash Customer-Account level, which means you can only have one template per Whiplash customer.
With a single account, it's possible for Wholesale to place an order and out-of-stock the web store, and vice-versa. Depending on your goals, this can be beneficial or harmful.
If you would like dedicated inventory levels for Wholesale orders, create a separate Whiplash customer. Then, transfer goods between the two accounts by creating matched Orders and Ship Notices.