If two devices have the same devnum and subsystem (more specifically, if the device is block or not), or have the same ifindex, then IDs of these devices are equivalent. Hence, the previous conditions are covered by comparing device IDs. Of course, events with a same ID should be already blocked by the devpath check. So, this should not change anything. However, udevd saves many kinds of data under /run/udev named with the device ID. If multiple workers processes events for the same device ID, then the database may become corrupted. Let's explicitly check the device IDs for safety and simplicity.
System and Service Manager
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