Modal Analysis using PDE Toolbox

I am trying to perform the modal analysis of simple beam with square cross section in order to calculate the Natural Frequencies and Modes (Fixed interface modes) in a specific frequency range. The problem is that the code returns a large number of modes, with some of them have almost identical natural frequencies. I am pretty sure i am not getting the right results, but i haven't manage to detect my error.

model = createpde('structural','modal-solid');

importGeometry(model,'Test.Part.stl');

generateMesh(model);
pdemesh(model)

E = 200E9;
nu = 0.26;
rho = 7800;
structuralProperties(model,'YoungsModulus',E, ...
    'PoissonsRatio',nu, ...
    'MassDensity',rho);

figure
pdegplot(model,'FaceLabels','on')

structuralBC(model,'Face',[1,2],'Constraint','fixed');

RF = solve(model,'FrequencyRange',[0,100]*2*pi);

modeID = 1:numel(RF.NaturalFrequencies);

tmodalResults = table(modeID.',RF.NaturalFrequencies/2/pi);
tmodalResults.Properties.VariableNames = {'Mode','Frequency'};
disp(tmodalResults);

Mode Frequency

____ _________

1 6.9322

2 6.9325

3 14.761

4 16.805

5 16.806

6 25.473

7 29.045

8 29.046

9 29.525

10 42.583

11 42.586

12 44.291

13 50.761

14 56.946

15 56.951

16 59.068

17 71.824

18 71.83

19 73.862

20 75.622

21 87.021

22 87.033

23 88.671

24 99.657