Core orbitals were frozen in all calculations as per the requirement of the (fc-CVS-)EOM-EE-CCSD framework, except for the N and O K-edge calculations for pNA wherein the lowest four and two core orbitals were frozen, respectively. The CVS-0 and CVS-uS 2PA cross sections with degenerate photons are computed between the CCSD and core-excited states, the latter obtained within the fc-CVS-EOM-EE-CCSD framework. We use the d-aug-cc-pVTZ basis set for NH 3 , t-aug-cc-pVTZ basis set for H 2 O and HF, t-aug-cc-pCVTZ basis set augmented with s and p Rydberg functions for Ne, uC-6-311(2+,+)G** for benzene, and uC-6-311++G** basis set for pNA. For each system, all core-excited states below the respective coreionization energies are considered-i.e., 10, 22, 24, 32, 65, and 63 states for NH 3 , H 2 O, HF, Ne, benzene, and pNA, respectively. The response equations are solved using an iterative Davidson-like subspace procedure. All spectra are convoluted using a Lorentzian broadening function with a half-width-at-half-maximum of 0.3 eV. In the discussion below, "X" labels the ground state and "c" a core-excited state