Questions about exciton strength

[Guo_BIT]

Dear developers:
I tried to analyzed the excitons using 'ypp -e s 1'. The lowest energy exciton is degenerate.

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#    E [ev]             Strength           Index
#
    0.414336473E-1     0.111063212         1.00000000
    0.414371118E-1      1.00000000         2.00000000

Both of them are mostly composed of transitions from VBM to CBM at 13th K-points (0.5, 0, 0)

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#    Band_V             Band_C             Kv-q ibz           Symm_kv            Kc q ibz           Symm_kc            Weight             Energy [eV]
#
         36                 37                13                 3                  13                 3                  0.982411           0.073429
         36                 37                13                 1                  13                 1                  0.982404           0.073429

I think this degeneracy arises from two degenerate K-points in the reciprocal space (0.5, 0, 0) and (0, 0.5, 0). Therefore, I attempted calculations without considering symmetry, and here are my results

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#    E [ev]             Strength           Index
#
    0.526852757E-1     0.198749393         1.00000000
    0.527218953E-1      1.00000000         2.00000000

and

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#    Band_V             Band_C             Kv-q ibz           Symm_kv            Kc q ibz           Symm_kc            Weight             Energy [eV]
#
         36                 37                289                1                  289                1                  0.982542           0.072616
         36                 37                13                 1                  13                 1                  0.982541           0.072652

among them, K-points 13 and 289 stand for (0.5, 0, 0) and (0, 0.5, 0), respectively.

Here are my questions
（1）Is my thought correct？
（2）More importantly, why is there such a significant difference in the strength of excitons generated by these two equivalent X points? I think they should be equal, and provide the same contribution to the absorption spectrum

[Guo_BIT]

The problem has been resolved，thank you