I would hazard a guess that record locking has not changed but they may have tweaked when the dialog is thrown. Kind of makes sense to me to only throw the dialog when actual edit data attempt takes place.
Search the FM knowledge base for changes in FM13 as I think I recall that there was a small change. I know that there is no control over this.
I want to say that the second user doesn't get notified unless they actually attempt to make an edit. I am pretty certain that both users don't have to be editing at the same exact time. Once User A makes an actual change to a field, the record is locked.
Imagine the scenario where User B clicks into a field for the purpose of selecting the value to copy to the clipboard. They aren't changing the field value in the locked record, so why bother them with a potentially confusing message.
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