Understanding the origin and diversity of emission processes responsible for Gamma-ray Bursts ( GRBs ) remains a pressing challenge .
While prompt and contemporaneous panchromatic observations have the potential to test predictions of the internal-external shock model , extensive multiband imaging has been conducted for only a few GRBs .
We present rich , early-time , multiband datasets for two \swift events , GRB 110205A and GRB 110213A .
The former shows optical emission since the early stages of the prompt phase , followed by the steep rising in flux up to \sim 1000 s after the burst ( t ^ { - \alpha } with \alpha = -6.13 \pm 0.75 ) .
We discuss this feature in the context of the reverse-shock scenario and interpret the following single power-law decay as being forward-shock dominated .
Polarization measurements , obtained with the RINGO2 instrument mounted on the Liverpool Telescope , also provide hints on the nature of the emitting ejecta .
The latter event , instead , displays a very peculiar optical to near-infrared lightcurve , with two achromatic peaks .
In this case , while the first peak is probably due to the onset of the afterglow , we interpret the second peak to be produced by newly injected material , signifying a late-time activity of the central engine .