Data were obtained for ALPIDE sensor at Vbb=0V and at Vbb=-3V using a 6 GeV/c pi^{-} beam  at the Proton Synchrotron at CERN.

TID and NIEL are calculated from the proton flux.
For 2.7 Mrad we had   total fluence of  F= 1.14763e+13   protons cm^{-2}.

NIEL is calculated as    NIEL = D*F        where D is taken from
https://rd50.web.cern.ch/rd50/NIEL/default.html
There one can find that for 30 MeV proton   D/(95 MeV mb ) = 2.346.
This gives total accumulated NIEL = 2.69e13  1_MeV_neq/cm^{-2}   which we
rounded to 2.7e13   1_MeV_neq/cm^{-2}.

TID is calculated  from the formula   TID [krad] =   1.60 E-8 * LET
[MeV*cm^2/mg] * F[cm^-2]
where LET for 30 MeV protons in silicon is  1.476E-02 MeV*cm^2/mg   (taken from SRIM).
Note that multiplying  1.60 E-8 * 1.476E-02 = 2.36e-02  yields a
number with mantisa  numerically  close to  D.
Therefore the mantisa for NIEL and TID looks very similar. It is coincidence for the 30 MeV proton energy.