"Insert trigger" - update column after insert

    CREATE TRIGGER [dbo].[TR_dbo_GlLoan_LoanNumber] ON  [dbo].[GlLoan] AFTER     INSERT 
AS 
BEGIN 
 if @@ROWCOUNT = 0
  return
SET NOCOUNT ON;

declare @count int; 
set @count= (select max(loannumber) from glloan where branchid=(select branchid from inserted) and CompanyId=(select CompanyId from inserted)) 
update glloan set loannumber=@count+1 where id=(select id from inserted) 
END

GO

Is there any chance where loan number can be duplicated for a given branch and company?