Density Functional Theory 1,2 (DFT) is the most popular methodology for computational chemistry calculations, in large part due to its efficiency compared to methods based entirely on wave function theory (WFT). Despite DFT being exact in principle, the functionals that describe electron correlation and exchange are not known and must be approximated. The success of DFT is therefore highly dependent on the selection of the density functional approximation (DFA). The number of available DFAs continues to grow steadily, with each new DFA attempting to more accurately describe challenging quantum-mechanical effects without significantly increasing computational cost. Initial DFT methods, based on the Hohenberg-Kohn theorems 1 and the Kohn-Sham equations, were only applicable to ground-state problems. In 1984, Runge and Gross developed equivalent theorems for excited-state calculations, paving the way for time-dependent DFT (TD-DFT). As TD-DFT requires an initial ground-state DFT calculation as input, its success is also dependent on the underlying DFA. In TD-DFT calculations, matrices for both single-particle excitations and deexcitations are used. However, computational cost can be decreased by using only the excitation matrix. This simplification is known as the Tamm-Dancoff approximation (TDA) leading to TDA-DFT applications. When considering DFT's metaphorical 'Jacob's Ladder', the description of electronic excitations with linear-response TD-DFT only becomes reasonable by using good representatives from at least the fourth rung of the ladder, namely hybrid DFAs, which combine semi-local exchange and correlation from DFT with non-local Fock exchange originally derived for WFT. Even better results for excitation energies are obtained when going to the fifth rung, namely double-hybrid density functionals (DHDFs) which improve the description of electron correlation by adding information from unoccupied (virtual) molecular orbitals in the form of a second-order perturbative component. Indeed, TD(A)-DHDFs following an approach suggested by Grimme and Neese in 2007 are known to be the most accurate DFAs for valence excitation energy calculations and absorption spectra in organic molecules, in some cases rivalling standard WFT methods. In the past, several attempts have been made to improve upon the initial TD(A)-DHDFs. Most notably those were the introduction of spin-component and spin-opposite scaling (SCS/SOS) to the perturbative part by Schwabe and Goerigk in 2017, and the introduction of range-separation to non-SCS/SOS TD-(A)DHDFs by Casanova-Páez, Dardis, and Goerigk in 2019. The latter improvement was an important step forward because prior to 2019 TD(A)-DHDFs following the Grimme-Neese idea had had the same incor-rect decay of the exchange potential and electron density as other global DFAs. This incorrect decay had caused global DHDFs to inadequately describe long-range transitions, in particular charge-transfer (CT) excitations. One popular attempt to combat this issue is range-separation, also known as long-range correction, which has been successfully applied to hybrid DFAs. The aforementioned work in 2019 followed the same spirit and introduced the first range-separated TD-DHDFs optimized for excitation energies called ωB2PLYP and ωB2GP-PLYP. They seamlessly connect hybrid-DFT exchange in the short-range regime of the electron-electron distance with 100% Fock exchange in the long range. Establishing 100% Fock exchange in the long range has been the underlying principle in most rangeseparated DFAs in the past, with the CAM-B3LYP hybrid being a notable exception. The strongly improved performance of ωB2PLYP and ωB2GP-PLYP has been demonstrated for singlet-singlet and singlet-triplet transitions, including for some infamously challenging localvalence, Rydberg, and CT excitations, such as polycyclic aromatic hydrocarbons. Further improvements of global and rangeseparated-in the exchange part-TD(A)-DHDFs have been achieved by our group in 2021 by revisiting the impact of SCS and SOS techniques. In SCS/SOS, the perturbative component of the electron correlation energy is split into energies of electron pairs of same and opposite spin and those components are individually scaled. For instance, in the original SCS-MP2 from 2003 this prevented the overestimation of same-spin correlation. By ignoring the same-spin part, SOS-based methods can achieve an improved formal scaling behavior, which makes them particularly valuable for larger systems. The superior performance of some of the fourteen developed SCS/SOSbased TD(A)-DHDFs has been demonstrated for singlet-singlet and singlet-triplet excitations with the best methods outperforming our original 2019 approaches, as well as some alternative DHDF definitions published in 2021, which also employ range-separation in the perturbative part. Nearly all benchmark studies exploring TD(A)-DHDFs dealt with closed-shell systems and assessments of open-shell systems have been rare and very limited in scope. In 2007, Grimme and Neese assessed TDA-B2PLYP on 11 small radicals. The only other two examples in the literature are the limited study of six open-shell atoms and seven molecular openshell systems with four global DHDFs. To our knowledge, no systematic study of openshell excitations has been conducted that also involves the latest developments in this area. Herein, we intend to close this knowledge gap. Our study will be conducted on a set of 45 doublet-doublet excitations in 23 molecular radicals initially presented and analyzed with WFT methods by Loos, Jacquemin and coworkers (Fig. ). In particular, we will compare TD(A)-DHDFs with hybrid functionals and separately address the impact of the TDA, range-separation and SCS/SOS on the excitation energies. Note that this radical set has later been included in the QUEST database, which comprises 470 excitations distributed over five sets, 38-42 some of which have been previously used by our group to assess TD(A)-DHDFs. This is the most thorough study of DHDFs on open-shell systems and it will provide insights on the current state-of-the-art in the field of DHDFT for excitation energies, which will inform us of whether they perform as well as for closed-shell systems or whether there is the necessity for further developments.