create table #t
( id int identity not null,
Name varchar(50) null)

insert into #t (name) values('Иванов  Иван')
insert into #t (name) values('Сидоров  Петр')
insert into #t (name) values('Петров  Дмитрий')
insert into #t (name) values('Чижиков  Иван')
insert into #t (name) values('Пупкин  Сергей')
insert into #t (name) values('Слонов  Слон')

declare @str varchar(50)
declare @name varchar(50)
declare @id int
DECLARE otpr_cursor CURSOR LOCAL FOR
Select id,name from #t
 OPEN otpr_cursor
 

FETCH NEXT FROM otpr_cursor INTO @id,@name

WHILE @@FETCH_STATUS = 0
BEGIN
set @str= @name 

Update #t
SET name=Replace(@str,'  ',' ')
where id=@id

FETCH NEXT FROM otpr_cursor INTO @id,@name
      
END
CLOSE otpr_cursor
DEALLOCATE otpr_cursor

select * from #t

drop table #t

while 2*2 = 4 begin
  update a
  SET name=Replace(a.name,'  ',' ')
  from a

  if @@rowcount = 0
    break
end

select
  replace(
    replace(
      replace(name, '  ', ' '+char(7)),
      char(7)+' ', ''),
    char(7), '')
from (
  values
    ('Иванов       Иван'),
    ('Сидоров   Петр'),
    ('Петров                    Дмитрий'),
    ('Чижиков    Иван'),
    ('Пупкин   Сергей'),
    ('Слонов Слон')
) v(name)