Redundant, annoying and wasteful vibrating while texting

My phone is set to vibrate on silent (which it is, usually), so it vibrates to alert me to texts when I'm not in the messaging app. Which is great, that's exactly what it should do and what I want it to do. What I don't understand then, is why it continue to vibrate to every text I receive from a person, as I have their conversation open in the messaging app. It's as if Apple wants to "alert me" to a message in a conversation that I am actively participating in and can already see, in real time. It's completely unnecessary, redundant, very, very annoying, and wasteful of battery life. How do I turn this annoying feature off while preserving the ability to vibrate outside of the application (when it actually is a relevant alert)? I don't want to turn off "vibrate on silent," nor do I want to go off silent mode.

Currently running iOS 7.0.4 on iPhone 5.