Created attachment 25112 [details]
Sample issue project
In UWP ItemAppearing is showing more items then a screen size.
I have listview with 1..to..1000 items.
Items visible on my screen is 51 and ItemAppearing event fired 255 times.
I have attached sample project also.
And solution to this issue is maybe this.
I don't know how to PR currently but in future I will.
Its working perfectly on android.
*** This bug has been marked as a duplicate of bug 58713 ***