I logged in this morning and this is what I found in my house!
I know this is an older thread, but I thought I'd respond.
What happens is the house is stored in your UO cache at that lfacet/x/y location on the other server you were on. Then when you switch to your shard, for some stupid reason, the client neither clears it's cache between shard switches, nor identify houses by location AND shard (note that I'm talking about the UO client cache, not the server). This leaves you with the old cached house, plus any houses on the new shard... and you get crazy building combinations!
This is worst when your flipping through multiple shards checking the same place. I did this to see if I could place a castle at a certain spot after a house fell. I thought that I might find the castle there on another shard to answer my question.... big mistake, lol. Every 3-4 shards, I'd have to close and reopen UO to clear the cache, otherwise I had to walk through a maze of broken houses that my client wouldn't even let me pass through (despite the fact that I knew they weren't there!).
It's a bug they really should fix, but I imagine it will never be fixed.
