So about half-orcs and half-elves...
Sure, in D&D they are their own races, but Revised Pathfinder adds an extra layer to them.
You see, Pathfinder has this thing called Versatile Heritages, which is a template which you can slap onto your character to make them different and get access to a series of different feats as determined by your character's race. The Player Core 1 book (Pathfinder's PHB but it's also the first half of the PHB) has a few like Changeling, Dhampir, various Aasimar/Tiefling variants, and other books have more. This is also where the Aiuvarin (half-elf) and Dromaar (half-orc) are found. You can only pick one of these per character, so no piling them on.
Now, the trick is that these two Heritages do not limit what they can be applied to. So sure you can be a half-elf gnome or a half-orc goblin, but you can also be a half-elf orc and a half-orc elf. These are two distinct characters with their own access to feats and their own stat blocks.
But it gets wackier. You can make the half-templates apply to their full counterparts. So yes, you can be a half-elf elf and a half-orc orc. Become Zormash Halforcen, the fierce warrior who is half orc and the other half is also orc! Or become Talanash Elfblood, the graceful bard who is forever apart from her people because aside from being a full-blooded elf she's also half elf.
Or for that extra wacky step, have an orc and an elf start a family and have all four variants be their kids! A half-elf elf, a half-orc elf, a half-elf orc and a half-orc orc. Hell, make them an adventuring party and have them see the world and create memories for the parent and siblings who are not cursed with the short orcish lifespan and so have something to remember half their family by for the decades to come.
