In this paper, we discuss the observation of simultaneously propagating dual-mode second-harmonic fundamental symmetric (s0) mode and a vertical-shear horizontal (sh0⊥) mode generated on an aluminium plate of 1 mm thickness while excited with a fundamental shear horizontal (SH0) mode in a large domain. The experimental observations, and numerical models, were used to confirm the presence of dual-mode second-harmonics. The two wavemodes would separate from each other in the time-domain, wherein the travel length exceeded a minimum cut-off length of 40λ. This approach can provide important implications for more versatile early state defect detection. © 2021 Elsevier B.V.