A predator-prey system is analysed where the transmissible disease can spread into the prey population. This will lead to a three-dimensional ecoepidemic model described by the temporal change of the healthy and diseased prey and the predator populations. The predator-prey interaction is modelled using the square root functional response such that the prey experience group defence: only the healthy individuals at the edge of the herd are consumed while the infected drift behind the herd. The predator feeds on both healthy and diseased prey individuals. The two prey populations are assumed substitutable so that a deficiency in one of the prey populations can be compensated by consuming the other. The resulting model for the trophic interaction is an extension of the classical Holling type II functional response for one prey population. Bifurcation analysis gives long-term dynamics of the boundary and interior equilibria, limit cycles and heteroclinic connections to saddle equilibria. The main goal is to gain insight into the effects of simultaneous predator feeding of both healthy and diseased individuals on the dynamics of the predator-prey system. With simultaneous feeding the feasibility of the system becomes smaller.