  We extend our study of energetic radio loud and quiet gamma-ray bursts
(GRBs), suggesting these GRBs potentially come from two separate progenitor
systems. We expand the sample from our previous paper (Lloyd-Ronning & Fryer,
2017) and find our results are strengthened - radio quiet GRBs have
significantly shorter intrinsic prompt duration, and are also less energetic on
average. However, the tenuous correlation between isotropic energy and
intrinsic duration in the radio dark sample remains tenuous and is slightly
weakened by adding more bursts. Interestingly, we find an anti-correlation
between the intrinsic duration and redshift in the radio bright sample but not
the radio dark sample, further supporting that these two samples may come from
separate progenitors. We also find that very high energy (0.1 - 100 GeV)
extended emission is only present in the radio loud sample. There is no
significant difference between the presence of X-ray/optical plateaus or the
average jet opening angles between the two samples. We explore the
interpretation of these results in the context of different progenitor models.
The data are consistent with the radio loud GRBs coming from a Helium-merger
system and the radio quiet GRBs coming from a collapsar system, but may also
reflect other dichotomies in the inner engine such as a neutron star versus
black hole core.
