The actual story of the droid is that it is an EG series, meaning more than one probably went into production, though the only versions we see is the EG-05 and the EG-07 droids, which are both similar in style and appearance. The EG-07 speaks but does not make any pain sounds, but the EG-05 does not speak at all, yet it does makes pain sounds. Having 4 of these EG droids would be rather ridiculous, it would be much better as a sub-boss for the level you speak of, having only 1 EG droid and having 3 different helper droids much like the story where you only face one iteration of him at any time.