Call simplify on your multigraph (you can tell if your graph or digraph is a multigraph using ismultigraph) to convert it to a simple graph.
s = [1 1 1 1 1 2 2 3 3 3 3 5 5];
t = [2 3 4 4 6 1 5 4 4 5 6 4 6];
names = string(1:6);
multiGraph = graph(s, t);
check = ismultigraph(multiGraph)
simpleGraph = simplify(multiGraph);
Let's compare how they look.
figure
h = plot(multiGraph);
title('multigraph');
figure
% Plot the simple graph with the vertices in the same location
% as the vertices in the multigraph
plot(simpleGraph, 'XData', h.XData, 'YData', h.YData)
title('simplegraph')
