When choosing 2 stickers with Size 15 cm and 1 sticker with Size 25 cm, this doesn't count for 3 same pieces.
"EigenTekst" : the input also has to be the same. 2 stickers "I love my dog" and 1 sticker " I love my cat" doesn't count for 3 same pieces.
The discount is only for exactly the same ordered items (stickers).
E.g.:
3 stickers "I love my dog" - 15 cm >>> discount OK : -20%
2 stickers "I love my dog" - 15 cm + 1 sticker "I love my cat" - 15 cm >>> discount NOT OK