These "guys" (yes, I know who "they" are, lol) also appears in Magma Taishi manga at times:
Here is a proof that Reno/Rino is Mamoru:
Note the antennae from his desguise, it's actually a updated version of Gam.
Also, pay attention in Mamoru and Gam's eye colors (OVA) and compare with both Reno and his desguise.
Unfortunatelly, I could not find reliable colored pictures of the original manga characters of Magma Taishi.
Humorously, Gam is younger and smaller than Mamoru in the Tokusatsu:
He is supposed to be a perfect double for Mamoru and he was even shown posing as him in the manga, despite the obvious antennae instead of ears, guess it would be difficult to make camera tricks with the same actor appearing at same time with different costumes in the tokusatsu.
Here is a close-up of Gam in the OVA:
In the OVA, Gam could even transform into Mamoru as seem in his first appearance and he is also able to change between human ears and antennae.
Knowing Magma Taishi, you may figure why Reno's desguise have a antennae.
Here is the versions of Magma (Magma is not reffered by name in the 2003 series, but it's obvious that is him due the golden complexion and the antennae):
In the Tokusatsu they could not make a golden make-up for the actor who played Magma, so they had to use a mask for the suit.
There is a suit actor dressed as Magma in the Mighty Atom 1980 series, but I'll show it separatelly.
Also, there is a doll of Magma which carry a sword in one of the episodes which I'll show other time.
Note:
Emily is NOT Gam, after all he was already used as a desguise for Reno/Rino.
I believe she is no one other than Chocola from Don Dracula.