From uptodate:
Pulsus Bisferiens: "The normal carotid arterial pulse tracing and the central aortic pulse waveform consist of an early component, the percussion wave, which results from rapid left ventricular ejection, and a second smaller peak, the tidal wave, presumed to represent a reflected wave from the periphery. The tidal wave may increase in amplitude in hypertensive patients or in those with elevated systemic vascular resistance. Radial and femoral pulse tracings demonstrate a single sharp peak in normal circumstances.
Pulsus bisferiens is characterized by two systolic peaks of the aortic pulse during left ventricular ejection separated by a midsystolic dip. Both percussion and tidal waves are accentuated. It is difficult to establish with certainty that the two peaks are occurring in systole with simple palpation (pulsus bisferiens) versus one peak in systole and the other in diastole (dicrotic pulse)."