Warning: Some input or output names are repeated.

clear;clc;
%first define given transfer functions
s=tf('s');
G1=1/(s+7);
G2=1/(s^2+2*s+3);
G3=1/(s+4);
G4=1/s;
G5=5/(s+7);
G6=1/(s^2+5*s+10);
G7=3/(s+2);
G8=1/(s+6);

sys=append(G1,G2,G3,G4,G5,G6,G7,G8);
%input and output label of appended system
sys.u={'x1';'x2';'x2';'x2';'x4';'C';'x4';'C'};
sys.y={'y1';'y2';'y3';'y4';'y5';'y6';'C';'y8'};
%define summing points for given block diagram
sum1 = sumblk('x1=R-x5');
sum2 = sumblk('x2=y1+y8');
sum3 = sumblk('x5=y2+y5');
sum4 = sumblk('x3=y3+y4');
sum5 = sumblk('x4=x3-y6');

M=tf(connect(sys,sum1,sum2,sum3,sum4,sum5,'R','C'));

Answer 1

[Chidvi Modala]

InputName property of tf function is used to identify channels on model display and plots. When sys.u is assigned to {'x1';'x2';'x2';'x2';'x4';'C';'x4';'C'}; x2, x4, and C are repeated which may not be able to serve the puporse of identifying channels and hence the warning