Some manufacturers will replace the ink storage foam inside a remanufactured cartridge to ensure the product achieves the highest quality possible.
Whether or not the foam will be replaced depends on the possibility of cross-color contamination, uniformity from cartridge to cartridge, and the manufacturer's personal standards. Strangely, some manufacturers have been known to replace the foam in all of the remanufactured ink cartridges in one line, yet none in another. The foam is often cleaned by way of a washer and dryer that the manufacturers have in their facilities so they can be reused, which prevents unnecessary waste.
Replacing the foam is not a requirement for remanufactured cartridges and is not always needed to produce a great quality product, so don't worry yourself wondering if your particular cartridge has had the foam replaced.