This paper starts with an observation that two infinite series of
simplicial complexes, which a priori do not seem to have anything to
do with each other, have the same homotopy type. One series consists
of the complexes of directed forests on a double directed string,
while the other one consists of Shapiro–Welker models for the spaces
of hyperbolic polynomials with a triple root.
We explain this coincidence in the more general context by finding
an explicit homotopy equivalence between complexes of directed
forests on a double directed tree, and doubly disconnecting
complexes of a tree.