Label construction is made up of two labels, where one label sits on top of the other label.
Piggy Back labels allow two individual labels to be applied at once, with the top label being removed.
The purpose of the Piggy Back is that the bottom layer of the adhesive will always be permanent, but the top adhesive label can be altered to suit different applications. For example, if the bottom label is being used for the sole purpose of carrying the top label then the top release liner is left blank or made of transparent material so substrate underneath can be seen.
It is commonly used on a return address label on parcels where a receipt can be peeled off and used.
In different applications top release liner may be printed with information that is either revealed when the top label is peeled off or is always visible.
The top layer of the adhesive is either permanent, when the top layer needs to be used as a permanent label elsewhere. Or dry peel adhesive, when the top label is peeled up to reveal the bottom label underneath or when the top label is removed but not reapplied elsewhere, such as coupons.