It's a bit more complicated than that as I played a different system in the past and had a source book for it that contained a number of aliens and that included the Devi Intelligence.
That book was first published in 1991.
I'm getting the rest of the info from the Traveller Wiki, so ...
Gurps Alien races 1 was published in 1998, so the Devi Intelligence predates it.
However there were a number of other alien races common to both Gurps and the other system.
From Gurps 1
The Drakarans
From Gurps 2
The Devi Intelligence
The Inyx
From Gurps 3
The Inheritors
The Lithkind
From Gurps 4
The Evantha
The J'sia (though they had a different name M'sia)
The Valkyrie
and finally and most interestingly, the Tezcat. (When I saw that they were appearing in AoCS 4, I thought I recognised them, so I went back and looked at the other book and then did some digging on the Wiki).
From what I've seen the aliens descriptions are very similar.
So since the Tezcat have already been covered in a Mongoose book, probably everything is OK.
Personally I think the Inheritors are really interesting, living on a partially completed Dyson sphere and are fluorine breathers!
There were other aliens in the book that haven't come over to Traveller as far as I can tell.
Avatars: Clouds of ionised plasma.
Metamorphs: Aliens who impersonate members of other races.
Shai-en-Rin: Enigmatic, powerful ships that nobody knows much about.
Sheol: Aliens that live in a gas giant. Two different species, living in a symbiotic relationship.
Spyders: Six-limbed omnivores that communicate by weaving webs.