exec sp_configure "allow updates", 1 
go

/* сохраняем себе на память, чтобы вернуть "как было"
select sysstat,type , name from sysobjects where name = "sysstatistics" 
sysstat     type name                                                                                                                                                                                                                                                            
----------- ---- ----                                                                                                                                                                                                                                                            
         97 s    sysstatistics                                                                                                                                                                                                                                                   
*/
update ..sysobjects 
set sysstat = 115, type = "U" 
where name = "sysusers" 
go 

/**REBOOT */

use DBANAME
go
/* получаем собственно дубликаты,  */

select * into tempdb..temp_sysstatistics from sysstatistics
go

select id, indid, partitionid, statid, colidarray, formatid, sequence, cnt= count(*) 
  into tempdb..temp_pkcols
  from tempdb..temp_sysstatistics
 group by id, indid, partitionid, statid, colidarray, formatid, sequence
 having count(*) > 1
go

select s.uid, s.suid
  into tempdb..temp_fixuid 
  from tempdb..temp_sysusers s, tempdb..temp_uid t
 where s.uid = t.uid
go

create index csysstatistics2 on sysstatistics(id, indid, partitionid, statid, colidarray, formatid, sequence) 
go
drop index sysstatistics.csysstatistics
go

/* удаляются не только дубликаты, но и остальные записи для этой группы статистик. мне не жалко было*/
delete sysstatistics
from sysstatistics s, tempdb..temp_pkcols t
where s.id=t.id and s.indid=t.indid and s.partitionid=t.partitionid and s.statid=t.statid and s.colidarray=t.colidarray and s.formatid=t.formatid and s.sequence=t.sequence

create unique index csysstatistics on sysstatistics(id, indid, partitionid, statid, colidarray, formatid, sequence) on "system"
go 

/* возвращаем как было */
update sysobjects set sysstat = 97, type = "s" where name = "sysstatistics" 
go 

/* REBOOT */

USE DBNAME
go 
dbcc traceon(3604)
dbcc checktable(sysstatistics)
go 
/*
The total number of empty pages (with all deleted rows) in partition 'sysstatistics_24' (partition ID 24) is 0. 
Mismatch between the 'ncfs counter' value (75) ....

зато успешно отрабатывает sp_fixindex!
*/
Exec sp_fixindex @dbname='DBNAME', @tabname='sysstatistics'

One or more indexes are corrupt.  They will be rebuilt. 
There are 994.000000 rows in 33 pages for object 'sysstatistics'. 
Non-clustered index 'csysstatistics' (ID = 2) successfully restored for object 'sysstatistics' in 'DBNAME' database. 
DBCC execution completed. If DBCC printed error messages, contact a user with System Administrator (SA) role.