Text in English, Danish & German. On 19 April 2008, professor John D Bergsagel celebrated his 80th birthday, and three weeks later -- on 8 May -- Professor Heinrich W Schwab attained the age of 70. The Department of Musicology at the University of Copenhagen and The Royal Library have decided to acknowledge the excellence of these two scholars by a double Festschrift, "A due". Both have been working at the Music Department of the University of Copenhagen and have collaborated with The Royal Library on various projects. This publication contains contributions from 44 colleagues, who thus -- in topics covering the period from the Middle Ages to the present day -- give their voice in the honouring of the two scholars for their musical scholarship. As it may be seen from the table of contents, the publication covers a broad range both in time and in topics, which are all included in the scholarly sphere of Bergsagel and Schwab.