I have a number of automated processes that send email reports. One of these reports is sending duplicate messages, which get caught by the Gmail conversation grouping and stacked appropriately. To find other occurrences of this, I'd like to be able to search for all messages that have a grouping greater than 1 that also match other search parameters. I haven't been able to find anything like this in the Gmail documentation, but I've found that's not always the best indicator of whether or not a specific feature does or doesn't exist. So...does this exist, either as an explicit keyword, or as some combination of other search terms?