Set<Account> accToUpdate 	= new Set<Account>();
Account acc = new Account(Name ='Test33');
insert acc;
accToUpdate.add(new Account (
							Id 					= acc.Id,
							Name				= 'Test'
					));
accToUpdate.add(new Account (
							Id 					= acc.Id,
							Name				= 'Test1'
					));
update new List<Account> (accToUpdate);