I have always been a little confused by the stamps in this issue. The Scott catalog describes the set as folk art. These two semi-postals the catalog says are (5.50z+1.50z) a choir and (7z+1.50z) an organ grinder. Hans Timmerman's site documents the first of the pair, saying it is a choir accompanied by a portativ organ. Even up close I have a hard time seeing an organ in either of them!
The set was issued in 1969. There were six stamps of regular issue (Scott 1705-1710) in addition to the two present stamps (B118-B119). The were issued in December of that year. The catalog does not give any details about the recipent of the special funds raised by the semi-postal stamps.
It does seem that the larger figure in B118 has hands hovering above a set of key. It's difficult to discern what the man in yellow pants is actually doing in B119. An organ of some type may be depict in either or both of these stamps! I include both of them mostly for a sense of completeness, since they appear on most persons' lists of pipe organ stamps.