They are the two professors from the "Time Machine" serial. They work in a laboratory, a secret room in the archeologic museum of Mouseton, in which they keep a lot of their inventions, and the greatest one is a time-machine.
First, Professor Zapotec appeared in "Topolino e l'enigma di Mu" (Topolino #1238-1239, August, 1979), by Massimo De Vita.
Then, after a few stories with Zapotec alone, Marlin appears on September 15, 1985, in "Topolino e il Segreto della Gioconda" (Topolino #1555), by Massimo de Vita and Bruno Concina.
The two professors are often arguying...
Both character often appeared together, in about 130 stories, but it
also happens that Zapotec appears alone (in about 40 stories). There is
even a story, "Topolino e il mistero dei Tecnechi", by Alessandro
Sisti, Maria Luisa Uggetti and Tiberio Colantuoni, in which Zapotec meets
Doctor
Einmug...
: go to Per Starbäck's page on Zapotek and Marlin.