@kitten you may mix words up (especially two new words that are pronounced or spelled the same) more often, but to some degree i think that is unavoidable. it also helps if you do them in different contexts and different learning methods for better separation (for example, maybe don't use flashcards for both). we are actively learning more than one language at the same time, though we would not recommend it with two similar languages
also French is in some things just so similar to Catalan, but at the same time it's different enough, which has its own kind of difficulty ("yes, I remember it was like this, but not exactly")
piss@lis@kitten doesn't it become a territory marking thing with the barking ones? There is a whole ritual of sniffing where someone else pissed and then pissing over the top.
Not sure how they'd react to a kitten pissing themselves though. Probably a similar way.