This is definitely a bug, and has been logged as bug #5814.
If you want to check for duplicate component ID's, the best way at the moment is to follow the instructions from this posting:
http://www.d-tools.us/general-section/2704-search-component-id.html#post8875
a. go to the Columns/Grouping menu in the PDM
b. in Columns, choose to show the Component ID field
c. in Groupings, uncheck 'Show packages and accessories'. Also, uncheck all groupings.
d. click on the Component ID column header to sort by component ID
At this point, you'll be able to see the component ID's for all products in your project, organized alphabetically. This will enable you to quickly scan for duplicates or other problems.