Virtualise and Page cause exception on non-unique list

[navozenko]

Virtualise and Page methods cause ArgumentOutOfRangeException if the list contains equal elements. Is it by design or a bug?

var source = new SourceList<string>();
source.AddRange(Enumerable.Repeat("item", 10));
source.Connect()
    .Virtualise(new BehaviorSubject<IVirtualRequest>(new VirtualRequest(0, 3)))
    .Subscribe();

or

var source = new SourceList<string>();
source.AddRange(Enumerable.Repeat("item", 10));
source.Connect()
    .Page(new BehaviorSubject<IPageRequest>(new PageRequest(0, 3)))
    .Subscribe();

Tested on version 7.4.9

[navozenko]

The exception seems to occur because Virtualise and Page use LINQ Except method to detect added and removed items.

var adds = current.Except(previous);
var removes = previous.Except(current);

This approach works fine when all items in the list are unique, but fails when there are equal items.

[RolandPheasant]

Out of interest, is there an obvious and easy alternative to using linq?

[github-actions[bot]]

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