Design principles of two-channel fluorescence probes are limited. Herein, we report a new principle, i.e., PET/d-PET (PdP) pairing, for the rational design of two-channel probes. Two fluorophores are required in such a PdP-type probe. They mutually quench their fluorescence via PET and d-PET. In the presence of an analyte-of-interest, such a PdP pair is converted into a FRET pair for signaling. The embodiment of such a principle is Rh-TROX, by tethering a rhodamine fluorophore with an ROS-sensitive probe (TotalROX). Fluorescence of both fluorophores in Rh-TROX was quenched as expected. The addition of highly reactive oxidative species led to the recovery of the fluorescence properties of both. The simultaneous fluorescence enhancement in two channels is a viable way to avoid false-positive signals. The new PdP principle could potentially be applied to the development of probes for another range of substrates.