Left join SQL Select Statement
You can try the following Command and make a left join on rate between both tables to get results as shown in your example 

SELECT t1.AccountID, t1.AccountName, t1.Rate, t21.Amount, t1.OldRate, t22.Amount
FROM table1 t1
/* LEFT */ JOIN table2 t21 ON t1.Rate = t21.rate
/* LEFT */ JOIN table2 t22 ON t1.OldRate = t22.rate