<p>Current thermoelastic models often isolate physical mechanisms, leading to inaccurate predictions for nanoscale semiconductor devices under ultrafast heating. This study establishes a unified spatiotemporal nonlocal dual-phase-lag (DPL) thermoelastic framework incorporating two-temperature effects and initial stress to analyze photothermal wave propagation in silicon. Unlike prior works that treat these factors independently, this model integrates spatial and temporal nonlocality with distinct conductive and thermodynamic temperature fields within a single continuum mechanics setting. The governing equations are solved semi-analytically using Laplace transforms and Fourier-series inversion. Results reveal a competing dynamic: spatiotemporal nonlocality acts as a stabilizing mechanism, attenuating peak thermodynamic temperature by up to 25% near the surface and 76% in the bulk, while reducing stress concentrations by over 50%. Conversely, the two-temperature parameter functions as an amplifying mechanism, sustaining conductive heat flow that increases subsurface thermal loads by over 300% and stress tails by 215% compared to single-temperature models. This demonstrates that neglecting either mechanism results in a systematic underestimation of thermal gradients and stress concentrations. The work advances semiconductor wave theory by quantifying the critical balance between nonlocal dissipation and two-temperature amplification, providing essential reliability guidelines for the design of optoelectronic systems operating under extreme photothermal conditions.</p>