I went on an adventure and came back to find all my villagers have duplicated so there are two of each. They are completely identical and have the same relationship status as their twin.

MCA is the only mod that I have so that isn't the issue. Hopefully he does resolve it because until then I'm turning into a serial killer to "deal" with the clones.

What's your MCA version and Minecraft version?

Sorry for the late reply.
MCA-5.0.6.1-1.8
Minecraft version 1.8 w/ Forge11.14.3.1450

When you see a villager like this, log out of the game and back in. Is the villager still there?

Yes. Also in my original comment I said they all have the same relationship status as their twin but this is false. The duplicates started with however many hearts the original had when they were created, but now any action I perform on one does not affect the other. Not sure how useful that info is.

Should be fixed in 8d7ab24.