When we have more than one entity named as the subject in a (here passive) construction, we use the word each to indicate that the verb-phrase applies to the nouns individually and not as a group:
Moe, Larry, and Curly have each been punched in the nose.
H C Gupta and five firms have each been named as an accused.
The same is true of active voice constructions; we use each to indicate that the subjects individually are doing the thing referred to by the verb-phrase, not acting as one:
H C Gupta and the five firms are each hiring lawyers to represent them.
That means each company is hiring its own lawyers; they're not sharing lawyers; they're defending themselves individually.