inusual guitar Some one Help me ?

Hi , everyone . I find this classic guitar today at the flea-market . I think it was a very special model and i never see it before like this . I suppose is a Guitar/bass becouse have 3 more cords may be for a bass player . Inside there is a target on paper bad in bad state it's wrote : (Milano - fece in Vignate 1961 ) and there is a U--ATO . I dont know nothing about this instrument . And i'm very glad to some one can help me in my reserch . Thanks to all the expert of collectors Weekly .
Albert