A new class of photonic channelized radio-frequency (RF) receiver is proposed and demonstrated. The new device relies on generation of high fidelity signal copies by wavelength multicasting in a self-seeded, two-pump parametric mixer. Signal copying to widely spaced wavelengths enables channelization of the full RF bandwidth using a single periodic filter. The channelization uses freely tunable frequencies of newly generated copies and eliminates the need for construction of a dense, narrowband filter bank. The new concept is demonstrated by channelization of four subcarrier channels with 1-GHz spacing and greater than 20-dB extinction ratio between extracted channels.