name for resized iphone 6 image

So ive always been able to get away with using the same image name in a line of code such as backgroundimage.png when applying a background image to a toolbar and when its deployed on an iphone 5 it automatically uses the backgroundimage@2x.png. Now that iphone 6 needs a resized @2x.png image as well how do i differentiate this in my code? what i mean is that now i cant just use the same image name for my resized 6 background image in my code as my original image.png because both the 5 and 6 would have the same name.

Am i supposed to write an if statement checking if the app is being ran on a 6 and then deploy my code with the specific iphone 6 image name @2x.png?