Steve, here is my story about PK with duplicates--------------
Server: Msg 8934, Level 16, State 2, Line 1
Table error: Object ID 517576882, index ID 1. The high key value on page (1:5667) (level 0) is not less than the low key value in the parent (0:1), slot 0 of the next page (1:11745).
Server: Msg 8933, Level 16, State 1, Line 1
Table error: Object ID 517576882, index ID 1. The low key value on page (1:11745) (level 0) is not >= the key value in the parent (1:5209) slot 21.
DBCC results for 'tblABC'.
There are 390047 rows in 9378 pages for object 'tblABC'.
CHECKTABLE found 0 allocation errors and 2 consistency errors in table 'tblABC' (object ID 517576882).
The real issue is the duplicate on primary key and on unique index-----unbelieveable !!!
Server: Msg 1505, Level 16, State 1, Line 1
CREATE UNIQUE INDEX terminated because a duplicate key was found for index ID 1. Most significant primary key is '432446'.
Server: Msg 8934, Level 16, State 1, Line 1
To face the reality. I have to drop all the indexes, including the clusterindex for PK and another concatenated unique index for (eventID, eventTime). Only at this point, I could run a sql query (having count(*) > 1) to find the duplicate records ---- 100% duplicate on all fields.
Finally, I could delete 41 duplicate records by create an identity field to distinguish them. The lesson I learned is there could be duplicates exceptions for anything including PrimaryKey field in SQL server.