ProGrid: What is the difference between a ProGrid unit with 8 mic preamps and 8 dual mic preamps

PG8-8MI-FXS : 16 Mic amps 
PG16-8DMPRE-FXS: 8 Dual mic amps 

There is quite a bigdifference. Both units are equipped with 8 Mic Inputs. PG8-8MI-xx has 8mic preamps 
While PG16-6DMI-xx has 16 mic preamp - each input isequipped with two preamps which can be controlled independently from 2different consoles.Using the PG16-8DMI would allow the operator at FOH and the operator doing the monitoring mix to each control the output (gain) from the same stage mic independently