We've never encountered this kind of MERGE-related race condition before, but I'm not sure that we'd recognize it if we did. Probably it would surface as a failed transaction, but our merges are pretty low-volume so it hasn't happened yet.
We were using merge for a year before load increased and we ended up having deadlocks. After finding this blog and a couple of others, we removed the merge statements, deadlocks went away.
We've never encountered this kind of MERGE-related race condition before, but I'm not sure that we'd recognize it if we did. Probably it would surface as a failed transaction, but our merges are pretty low-volume so it hasn't happened yet.
Thanks for the link!