That makes it even more weird. So it's a port of a port that is running on compatibility mode.
Yeah, though considering nothing changed between anniversary's standalone appearance on 360 and it in mcc on xbox one I consider it one port total. Like when 360 games are made backwards compatible for xbox one, there is some small work involved but they aren't considered ports and you can even use the original disk.
Halo:CE has gone through crazy amounts of porting when you think about it. MCC PC CE is being ported from Anniversary/MCC CE which is ported from the Gearbox PC port of CE which was ported from the original Xbox CE...Halo Anniversary being originally an Xbox 360 release right?
As a sidenote, the original Halo CE PC is considered broken. A "fixed" version exists on the Custom Editon branch which is derived from the PC release.
No wonder they never made a Halo 2 Custom Edition!
Actually, the reason for there not being a Halo 2 Custom Edition is because when Halo 2 was ported to the PC in 2007, its editing kit was kneecapped and stripped of so many components to the point that it couldn't do half of the things that Gearbox's release of Halo CE could do, and the documentation that was included for things like setting up dedicated servers was so vague as to be completely useless. The officially released H2EK was pretty much a shadow of the original Custom Edition's HEK that pretty much no one outside of the dedicated modding community even touches it, and even then the population is minuscule in comparison to Halo CE's modding population. And H2EK wasn't released by a third party, it was released by Microsoft themselves through a small internal team that was eventually dissolved a short time after Halo 2 Vista's release, so the players and modders have pretty much had to navigate blindly and create their own documentation for how to use and do pretty much ANYTHING. That's why there's no official Halo 2 Custom Edition. Microsoft's aggressive push for DRM requirements was also part of the reason, as well as the fact that Halo Vista could only be activated 3 times per machine, unlike Halo CE which could be uninstalled and reinstalled an unlimited number of times on any machine as long as you had a valid product key.
Also, the fixed version of the Halo CE PC port is called the Refined version, but you need custom edition to play it, so whip out that Halo 1 PC product key and install that game!