how to prevent of repeated permutation

I have written this

X =rand (4,2)
t= size (X);
permlimit = 100;
M2 = zeros([permlimit, t(2)]);
for ii = 1 : permlimit
 for jj = 1 : t(2)
      M2(ii,jj) = X(randi(t(1)),jj);
  end
end

But in out put I have some similar result, I do not want to have, how to prevent having them ? for example I will have in my results M2 =

    0.3897    0.1171
    0.3335    0.1604
    0.3335    0.1171
    0.3337    0.1604
    0.3897    0.5503
    0.3337    0.1171
    0.3897    0.1604
    0.3337    0.1604
    0.3337    0.1604

As you see some of results are the same like

 0.3337    0.1604
  0.3337    0.1604

[Andrei Bobrov]

Number permutation for matrix with size 4x2 in your case: 16, ie will repeated rows

Answer 1

[Thomas]

 unique(M2,'rows')