Thanks for writing.
In RadJumpList, items arrive in the groups in the order they appear in the source collection. When an item is replaced, the new item has no group and our Data Layer tries to find a group for it according to its group key. When the group is found, the item is appended at the end of the group since the logic is the same as if you have removed the old item and added a new one. In other words, when replacing an item, we cannot know that the new item will have the same group.
If you are sure that when replacing items the new ones will remain in the group of the previous one, you can simply overwrite the properties of the new item over the old one without actually modifying the source collection.
I hope this helps.
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