Swift GRB 100418A is a long burst at z = 0.624 without detection of any associated supernova ( SN ) .
Its lightcurves in both the prompt and afterglow phases are similar to GRB 060614 , a nearby long GRB without an associated SN .
We analyze the observational data of this event and discuss the possible origins of its multi-wavelength emission .
We show that its joint lightcurve at 1 keV derived from Swift BAT and XRT observations is composed of two distinguished components .
The first component , whose spectrum is extremely soft ( \Gamma = 4.32 ) , ends with a steep decay segment , indicating the internal origin of this component .
The second component is a slowly-rising , broad bump which peaks at \sim 10 ^ { 5 } seconds post the BAT trigger .
Assuming that the late bump is due to onset of the afterglow , we derive the initial Lorentz factor ( \Gamma _ { 0 } ) of the GRB fireball and find that it significantly deviates from the relation between the \Gamma _ { 0 } and isotropic gamma-ray energy derived from typical GRBs .
We also check whether it follows the same anti-correlation between X-ray luminosity and the break time observed in the shallow decay phase of many typical GRBs , which is usually regarded as a signal of late energy injection from the GRB central engine .
However , we find that it does not obey this correlation .
We propose that the late bump could be contributed by a two-component jet .
We fit the second component with an off-axis jet model for a constant medium density and find the late bump can be represented by the model .
The derived jet half-opening angle is 0.30 rad and the viewing angle is 0.315 rad .
The medium density is 0.05 cm ^ { -3 } , possibly suggesting that it may be from a merger of compact stars .
The similarity between GRBs 060614 and 100418A may indicate that the two GRBs are from the same population and the late bump observed in the two GRBs may be a signal of a two-component jet powered by the GRB central engine .