> ITMX: 168.300, 174.250, 178.375, 179.375, 184.750, 187.250
> ITMY: 176.500, 179.875, 182.250, 184.750

184.750Hz mode is included in ITMX and ITMY.
Is this mean that two peaks are too close and degenerate in the current frequency resolution?

Frequency values shown by Tamaki-kun seems 0.125Hz resolution. But he measured with 1mHz resolution according to his klog.
It may be better to check the reason why all frequency shows .125, .375, .500, ...

Anyway, I tried to add the annotation for the nearest peak of DARM sensitivity with 1/1024Hz resolution as shown in Fig.1.
All peaks are matched within 0.06125Hz (=0.125 / 2) between Tamaki-kun's list and DARM peaks with 1/1024Hz resolution.
So almost all annotations seem to be reasonable if my assumption that Tamaki-kun's list is 0.125Hz resolution is correct.

On the other hand, we can see two-peak pairs that frequencies are close within 0.1Hz such as
- 167.103Hz and 167.195Hz (correspond to the ETMX 167.125Hz in Tamaki-kun's list)
- 181.760Hz and 181.837Hz (correspond to the ETMY 181.875Hz)
These two annotations may be wrong.

Though the 1st violins located from 165-195Hz, peaks which seems to be the 2nd violin located above 400Hz instead of 330-390Hz as shown in Fig.2.
I had though the 2nd violins located roughly twice frequency of the 1st violin.
Is the difference of a few tens Herz from twice frequency of the 1st violin reasonable?

It is reasonable because the sapphire fiber is relatively thick compared to the suspended mass.
If the fiber were thin enough, the resonant frequencies of the violin modes would be determined by the tension in the fiber, and the second mode would be nearly twice the frequency of the first mode.
However, in the case of the KAGRA sapphire fiber, it is thick enough to influence the resonant frequency through the elastic restoring force.

For the KAGRA fiber, the frequencies of the first and second violin modes are 175 Hz and 410 Hz, respectively.
The ratio of 2.3 (= 410/175) is consistent with the measured value.