Iphone 4 alert goes off twice?

I get a text and my phone chimes like normal. A few minutes later it chimes a few minutes later. How do i turn it off?
Its for normal txt messages

App for iPhone that Will Make Life Easier?

Is there an app besides bump that shares info?
And what are apps on both the Android market and App Store that are compatible for video calling? So I can check in on family who don't have FaceTime.

How much should I sell my iPhone 5 for? Read below?

I have a white 16GB Sprint iPhone 5 that I'm getting ready to sell on ebay. Its only 2 weeks old, comes with mirror screen protector, comes with $40 otter box commuter case, comes with $10 tpu case, comes in original box with OEM Apple charger. I'm not sending the earpods with it though because I used those. This phone can also be unlocked. Because of it being in absolute brand new condition, I was thinking of selling it for around $590. What do you think? And it cost around $709 after tax from an store.

Iphone or basic phone + ipad?

I love my iphone 4s, but I alone pay $100 dollars per month for the phone. What's your opinion on having a cheap phone and ipad (just Wi-Fi) vs. Iphone and that lovely bill? Have you thought of the idea?

Added (1). Don't get me wrong Robert, I love my iphone but its monthly price vs.product value.