Besides his numerous studio albums, André Hazes also recorded many songs that didn't make it onto these regular albums, including tracks released as separate singles or B-sides, duets with other artists, and songs he recorded specifically for "best of" albums as extras. These songs are now collected on the 2-CD set "Curiosa." This comprehensive album contains a total of 43 tracks not found on André's regular albums, including the German versions of "Amor, Amor, Amor," "Zo Heb Ik Het Nooit Bedoeld," "De Glimlach Van Een Kind," and "Vaag En Stil" (Vague and Still). There are also duets with Herman Brood, Piet Römer, Willeke Alberti, Paul de Leeuw, and of course, the new duet "I've Been Loving You Too Long" with Gerard Joling.