Hi Daniel,
You dont need to delete any of your photo's as it is your personnel photo gallery and it does not matter if there are several photos of the same aircraft from different photographers.
I would suggest doing what Nick has suggested, If you feel you have taken a better photo than one you already have, then it is your decision to remove a lesser quality photo.
One thing to remember, no two photos are the same, they capture a moment in time and tell there own story.
cheers
Chris Hall
Airport Data Admin Team