This was working in OpenOffice, but not in LibreOffice. To reproduce: 1. create a 1-column table in Writer with the following content: === 00:30:00 00:15:00 01:30:00 === 2. (optional) highlight the created column, right-click on the selection, click on "Number Format...", click on "Time" in the left pane and "876613:37:46" on the right pane, and click on the "OK" button; 2. open Calc and highlight column A, then right-click on the selection, click on "Format Cells...", chose "Time" in the left pane and "876613:37:46" on the right pane, and click on the "OK" button; 3. copy-n-paste the content of the table we created in step 1 to column A. Expected result: all three rows should have been recognized properly, i.e. 00:30:00, 00:15:00, 01:30:00. Observed behavior: some kind of auto-detection kicks in during the copy-n-paste and all inserted items are recognized as 12-hour time stamps, e.g. 12:30:00 AM, 12:15:00 AM, 01:30:00 AM.
Ok, I've just checked that the current version (on 2012-07-10) of LibreOffice works as expected. Closing this bug.