You could require only one icon to be moved by number at a time, if it presented an issue.
Or you could just say "when all is said and done, order them by the numbers they now have. If two icons have the same number, put them together, and keep them in the order they had on the page."
So if you have: 001 RED ICON 002 SAD ICON 003 SLEEPY ICON 004 ANIME ICON 005 FOOD ICON 006 BLUE ICON
And you edit to: 001 RED ICON 002 SAD ICON 005 SLEEPY ICON 004 ANIME ICON 005 FOOD ICON 001 BLUE ICON
When you save, you'd end up with:
001 RED ICON 001 BLUE ICON 002 SAD ICON 004 ANIME ICON 005 SLEEPY ICON 005 FOOD ICON
no subject
Or you could just say "when all is said and done, order them by the numbers they now have. If two icons have the same number, put them together, and keep them in the order they had on the page."
So if you have:
001 RED ICON
002 SAD ICON
003 SLEEPY ICON
004 ANIME ICON
005 FOOD ICON
006 BLUE ICON
And you edit to:
001 RED ICON
002 SAD ICON
005 SLEEPY ICON
004 ANIME ICON
005 FOOD ICON
001 BLUE ICON
When you save, you'd end up with:
001 RED ICON
001 BLUE ICON
002 SAD ICON
004 ANIME ICON
005 SLEEPY ICON
005 FOOD ICON