[mothered]

I was wondering what the companies that check the seals then do with the products once they have opened the seals (from legitimate returns). Do they reseal them with new seals to sell them again as new product or do they put them back on sale as repackaged products?

It's Impossible to speak for each and every company.

Some have the factory seals on hand, thereby reseal the packaging and sell the goods at the usual retail cost, while others dispense them at a discount price. And then there's those who mark them as a tax write-off.