Route-flow nonuniqueness at a Wardrop equilibrium

Strictly increasing link delays make Wardrop equilibrium link throughputs unique, but route decompositions of those throughputs can differ. With unit demand through two successive stages of two parallel links each and link delay $D(u)=u$, the four-route vectors $(t,1/2-t,1/2-t,t)$ for $0\le t\le 1/2$ all induce link loads $1/2$. All routes then have equal delay one.