The interactions of cascade remnants with freely migrating defects (FMDs) during dual light and heavy-ion irradiations in Cu-lat.%Au at 400°C were investigated using Rutherford backscattering spectrometry. Near-surface Au depletion driven by 1.5-MeV He ion irradiation was suppressed by concurrent bombardment with 1.2-MeV Ag ions. The dual irradiation effect suggests that shortlived cascade remnants created by heavy ions act as recombination centers for FMDs, reducing radiation-induced segregation (RIS). The effects of the total cascade volume generated by heavyion beams on the suppression of RIS were examined. The investigation revealed when 800-keV Cu and 1.2-MeV Ag ion beams produce nearly the same total cascade volume per second, their suppression effects on 1.5-MeV He-induced Au transport are also nearly equal even though the total cascade volume produced per ion for each are different. This result indicates that the suppression effect of cascade remnants produced by heavy ions depends on the total cascade volume induced per unit time and not on the total cascade volume per ion generated by individual ions of different mass and energy.