xferguson
commented
11 years ago I added an alert() and some console.error messages. You can always comment some of that out if you don't want it, but I think it's all helpful.
The duplicates are deleted from the data set. Yes, this does cause parents to get confused, but they were being confused anyway.
If two or more items have the same UID, my browser becomes unresponsive. HGrid should probably raise an error instead, or remove the offending item(s) with a warning.