Is it weird to chat with the same person in 2 different apps, and have different conversations in each, at the same time?
I've been chatting with this girl I really like. Mostly, we chat on Facebook, but sometimes she'll send me a cute snap, and we'll open a different conversation on Snapchat. Then we chat in both apps, but it's 2 different conversations.
short answer: no
long answer:
It's normal to switch back and forth between topics in a conversation. The apps are just tools that help to sort it. And you don't have to say, "oh, and one more thing regarding the pic you sent me earlier..." and stuff like that all the time
Pretty handy imo, nothing wrong with it.