Any Studio Energy users here? Question about this phone

[Oddworld17870]

Studio Energy was my first Blu phone, and I loved it, but I had to replace it the speaker blew out. To those of you who have it: when you plug an external speaker into the jack, does it cancel out your internal speaker? I'm sure it's supposed to, but mine didn't, and playing music at work all day everyday was too much for it. I want to get another one, but I wanted to make sure this isn't a flaw in all of that model.