add a product to an opportunity

I have a product table on a wizard page. I have a row action on each row of the product table that creates a new record in the OpportunityProduct table, and attaches the product listed to the opportunity created in an earlier page of my wizard.
For the first product, it works great, but if I try to add a second product (using the action button) the first product gets added again. I have tried to clear the model, but the removes the whole product table.
Any ideas?

Hello Tyler

would you mind sharing the page XML? I assume you could ease up the process with employing one or two models which you only use while adding the product and clean up afterwards but i honestly can’t think it properly trough without seeing how you have engaged the problem already.