I tried to introduce Chalupa and Persephone last week. I've never seen either of the girls spray before, but there they were spraying and getting into "chinchilla attack mode". Persephone pulled a lot of fur, but Chalupa was content in the new area, eating some hay and playing with a toy like nothing was different. We separated them again a few minutes later and tried again at night, this time Chalupa was territorial too and she ended up losing more fur than I was comfortable with, and Persephone was making this menacing noise I've never heard from a chinchilla before, and we separated them again. Persephone bit me and I cried because I had been working so hard with the girls and cared so much about them, and I was afraid the attempt to put them together would turn Persephone against me.
Now they're separated, and I haven't tried taking them out for playtime together again, even though I'd done it in the past and they were fine together. Both are still warming up to me well, and I'm glad, but I don't think we're going to try to introduce them again. I can't stand seeing them fight like that and I don't want to risk it.