Guess what's back?

[Renegade]

@pd: That may be true, but both Ares.dll and Ares.dll.inj are "foreign" to the game, whereas .mix files are not. (i.e. there was no traditional way to name them, whereas there is one for the mix.)

Naming it expandmd02 also has the additional effect that it's more noticeable.
expandmd02 will sit right under 1.001's expandmd01 and above any TX or mod mixes, making it very clear that next to YR 1.001, TX and SomeRandomMod, Ares is installed as well.
If you put it as Ares.mix instead, it'll be sorted elsewhere, far away from the normal stuff, ready to be forgotten.

On top of that comes an even simpler issue: Windows.
Default (read: most) Windows installations don't show file extensions to the user. Which means, if you name it Ares.mix, normal users will see

Code:

Ares
Ares.dll
Ares

While that should not be an issue for normal users, remember how Launch Base created 0 byte Syringe .exes.
Imagine a similar issue with Ares - do you really want to have a three-day-conversation with a newb because he's checking the file size of the wrong "Ares" or "Ares.dll"?
Or want them complaining that Ares.mix is corrupted when they try to open Ares.dll?
Telling you that no, they are not trying to open Ares.dll, because they can clearly see "Ares.dll" in the file listing?

Ares.dll and Ares.dll.inj are parts of the Syringe injection system.
The mix holds traditionally loaded game content.
The files serve totally different purposes, and, as such, I don't think it's really all that bad that they have totally different names.

expandmd02.mix is the way to go.