I do not know how to fix this, but the system seems to keep eating the tag 'two_tails' in favor of 'twin_tails'. Here is an image that should have both:

https://e621.net/post/show/7826/

'two_tails' would refer to a character in the picture having not one, not three, but two tails. To three thou shalt not count!

'twin_tails', on the other hand, actually refers to the hairstyle of having the hair gathered up on either side of the head, like Kasane Teto or the well-exposed tigress in the above image. I am sure this has affected a lot of images and I am not sure how to fix it, but I feel it should be fixed.

https://e621.net/forum/show/91990

Dunno what that link has to do with it..
It's not getting mixed up with twin tails. But two_tails is aliased to multiple_tails, which is already tagged.
There are no specific tag for more than one tail, they're all currently lumped under multiple.

It always struck me as odd that we have separate tags for the number of toes, fingers, etc. But not for tails.

Genjar said:
Dunno what that link has to do with it..

Nah, just posting a similar thread related to the topic