Actually what I wanted to do: to create site template to use for all users. On first page place journal article with information about users, so, journal article automatically placed on users sites and each user may change information about himself.
So, to reproduce this bug we need:
1. (not actually required - but used in my case: set journal.article.force.autogenerate.id=false in portal-ext.properties)
2. Create site-template
3. Place "Display Journal Article" portlet on first page
4. Create empty journal article with id "ABOUT-USER"
5. Create new user, during create choose created site template for public pages
So far everything is ok - new site for new user is created. During export-import of site template into user public site journal articles was migrated to new group. "Display Journal Article" portlet configuration was changed, so, it is displayed "ABOUT-USER" web-content from created user groupId.
6. Change something in site template
7. Refresh public user page
Now, during changes propogation from site template into user site portlet preferences was replaced, including preferences for "Display Journal Article" portlet - so, it is now displayed "ABOUT-USER" article - but from "General" group - not from user specific. As result, all sites created from this template displayed same journal article - not specific for each user.