I think kcott is entirely correct. I'm going to have to check this a bit closer for other cases of such duplicates. There may be another way of doing this that I missed. Thanks. For now, my db is updated and it shouldn't mess up Polyglot again.
By the way, more effective way to get me is through a /msg - I'm obviously not paying real close attention to the list of nodes these days :-S, and when I do actually bring up the site in my browser, we know I'll see the message. Even more immediate, though slightly less effective, is just to mention it in the CB - I will probably get a message from my IRC client that someone mentioned my name. On the off chance that I miss that, though, I miss it forever :-) Some people try mentioning my nick in the CB, and, if that doesn't elicit a response within usually 10 minutes, send the private message.
Update: I think I got this fixed now. When I get a message from PM, the user ID comes along. I was ignoring it. Now I'll use it to immediately check if I have it in my local cache, and, if not, it'll get inserted immediately. Up to now, I've been relying on looking up the user later, which then means doing what kcott implied: looking for node=$user, and failing if I get back the disambiguation page. Now I'll have the number immediately, look it up by node_id instead, and it should work every time. Again, thanks for the report.