How does the undomanager solve multi-user operation conflicts?

For example: There is an array. User A deletes { name: a } at position 0, and user B inserts a new value { name: a } at position 0. User A cancels. At this time, two records of { name: a } will appear in the array.

I would like to ask if the undo manager considers this conflict in the above situation?

I’m not sure what you mean by “cancel”. But when user 1 performs an undo, then two elements { name: a } will appear. If you don’t want duplicates, you could filter-out duplicates.