I suppose the answer could apply to any instance, but I'm mostly referring to this one.
Mind you, I don't have two accounts, but I'm considering it: one for memes, the other for serious discussion.
But I'm unsure if that's considered bad form by most people, so I thought I'd ask.
Thanks!
EDIT: Also, come to think of it, even if it were okay, would it even be possible to have to be logged into two separate accounts on the same instance at the same time with the same browser profile? :/
Na. Multiple accounts is fine as long as you don't vote manipulate.
It's also a good idea if you run communities. One account as your daily driver and the other for administrative actions.