The ‘+’ operator connects the two ‘G’ models in parallel. They do appear to have pole-zero cancellation as the result:
s = tf('s');
G = 8.75*(4*s^2+0.4*s+1)/((s/0.01+1)*(s^2+0.24*s+1)*(s^2/100+2*0.02*s/10+1))
GG = G+G
figure
pzmap(GG)
Calculating the minimum realisation solves the problem:
GGmr = minreal(GG)
figure
pzmap(GGmr)
