Check your head at the door

Tiff was asked to deposit a check but wasn't given a deposit slip. She was told she could get one at the bank. She was concerned because she didn't have the account number and I agreed that she should find out what it was. Then she looked at the check, pointed to the numbers at the bottom and exclaimed, "Oh, here it is!" 

 I said, "No, that's our account number." 

She sniffed, "How do you know?" 

 I took a deep breath and said, "Because that's the account the check is drawn on." 

"Well, maybe he wants it deposited there." 

"Why would he write a check and then redeposit it into the same account?" 

"I don't know. Sometimes the things he wants don't make sense. Oh, wait - what's this number written on the back?" 

"That must be the number for the account he wants the money deposited into." 

"Are you sure?" Sigh.