We study the dynamics of dark-bright (DB) solitons in binary mixtures of Bose gases at finite temperature using a system of two coupled dissipative Gross-Pitaevskii equations. We develop a perturbation theory for the two-component system to derive an equation of motion for the soliton centers and identify different temperature-dependent damping regimes. We show that the effect of the bright ('filling') soliton component is to partially stabilize 'bare' dark solitons against temperature-induced dissipation, thus providing longer lifetimes. We also study analytically thermal effects on DB soliton 'molecules' (i.e. two in-phase and out-of-phase DB solitons), showing that they undergo expanding oscillations while interacting. Our analytical findings are in good agreement with results obtained via a Bogoliubov-de Gennes analysis and direct numerical simulations.This model incorporates a damping term (accounting for finite temperature), first introduced phenomenologically by Pitaevskii [27], and later shown to be relevant from a microscopic perspective (see e.g. the review [28]). It is important to note that, as shown in [17], the analytical results obtained in the framework of the DGPE were found to be in very good agreement with numerical results obtained in the framework of the stochastic Gross-Pitaevskii equation (SGPE); see e.g. [29] for a review on the SGPE model. It should also be mentioned that while the above works chiefly considered finite-temperature effects for the case of a single dark soliton, the DGPE model and the anti-damping-incorporating ordinary differential equations (ODEs) for the soliton center were also examined in the case of multiple dark solitons. In particular, the cases of two and three oscillating and interacting anti-damped dark solitons were considered in [30].In this work, we study the finite-temperature dynamics of DB solitons in harmonically confined Bose gases. In particular, we adopt an effective mean-field description and analyze theoretically and numerically a system of two coupled DGPEs, describing the evolution of a binary quasi-one-dimensional (1D) BEC at finite temperature. We extend the considerations of [17] and develop a Hamiltonian perturbation theory for the two-component system at hand. This way, we obtain an equation of motion for the DB soliton center, similar to the one derived in [15,17]. This equation, which includes an anti-damping term accounting for finite temperature, provides a characteristic eigenvalue pair (i.e. a pair of solutions of the characteristic equation associated with the linear equation of motion), which is connected to the eigenvalue associated with the anomalous mode of the DB soliton. Performing a BdG analysis, we show that the anomalous mode eigenvalue becomes complex as the dissipation (temperature-dependent) parameter is introduced, leading to an instability of the DB soliton pair. The temperature dependence of the eigenvalues (determined analytically) is found to be in good agreement with the relevant anomalous mode eigenvalue (determined nu...