This is one that, in five years of dealing with the search engines, I have never seen before.
Anyway, here's the scenario:
I have an IT company website which has two mirrored domain names: adamitpros.com (for offline marketing purposes) and adamitpros.ca (which I use for search engine reasons to try and attract region-specific traffic).
Here's where it gets interesting:
Since I use the .ca for online promotion purposes, I have never acquired a backlink to adamitpros.com. I have, however, acquired a series of backlinks to adamitpros.ca. So no backlinks for .com, a bunch for .ca. Which means the .ca would be the one that should be indexed, right?
In the case of MSN and Yahoo!, no. The .com is, but not the .ca.
(Note: I know there are no meta tags in the description since I really haven't bothered to run a full campaign on it yet. I just put it up quick).
Are there any explanations on this one from the peanut gallery?