when you have document with DocumentUrlPath set and some links to it in different catalogue branch - some strange behavior can appear. Especially when other catalogue nodes are of some different structure.
Forexample - when we have doc with docurlpath /mydroduct (www.mysite.com/myproduct) and some link-docs to it, kentico engine use this query to determine path

(SELECT TOP 1 * FROM View_PageInfo WHERE ((NodeSiteID = 1) AND (DocumentUrlPath = N'/myproduct') AND (DocumentUrlPath <> NodeAliasPath))) UNION ALL (SELECT * FROM View_PageInfo WHERE ((NodeSiteID = 1) AND (NodeAliasPath = N'/myproduct') AND (DocumentCulture = N'en-EN')))

without "TOP 1" it rerurn all of aliasnodes and the main node.
in result with "TOP 1" there can be ANY of alias nodes with this documenturlpath - its the way TSQL top-engine works. It return the most "quickly-returnable" item :)

so nodealiaspath - (the thing we want to know for future) - can be any of nodealiaspath

then if you have breadcrumbs (for example) it shows you the way to your random alias ))

For my project i fixed it by adding "and (NodeLinkedNodeID is NULL)" to query.text

now it looks like this:

(SELECT TOP 1 * FROM View_PageInfo WHERE ((NodeSiteID = 1) and (NodeLinkedNodeID is NULL) AND (DocumentUrlPath = N'/myproduct') AND (DocumentUrlPath <> NodeAliasPath))) UNION ALL (SELECT * FROM View_PageInfo WHERE ((NodeSiteID = 1) and (NodeLinkedNodeID is NULL) AND (NodeAliasPath = N'/myproduct') AND (DocumentCulture = N'en-EN')))

it works)