I may have sent books to the wrong person.  I had three requests.  My procedure is to take the book, place it, with the envelope and three or four sheets of paper, on the scale to get the weight.  Then put than in as the weight for the postage to be printed. 

I then place the envelope on the table, put the printed page on top and then the book.  Wrap the book in plastic to protect it, put it in the envelope with the section to be sent then seal and put the address on the envelope. 

Hubby decided to help as he was in a hurry to leave.  W get to the post office and the first book weighs in fine.  She weighs the second book and it is short by 48 cents.  Weird, but okay.  Give her the change and she adds a stamp.  Then she weighs the third book.  It is over.  Weighed in at 1 lb and I had paid for the postage of 1 1/2 lbs. 

Now, I am beginning to worry that I could have switched the books.  I weighed them as 11 oz, 12 oz and 1 lb and 2 oz. 

What should I do?  One I double checked and I know she will get the right book. The other two, they could have been switched. 

Do I pm the requestors and let them know that the books could have been switched?     Ask them to mail them to the correct person?  I will refund them their credit and give them another credit as an apology, but what else should I do? 

Beside tell hubby I appreciate his offer to help, but I can handle it fine on my own.  I don't want a repeat of sending the wrong book!  

Pm the two that might be confused. Ask them to PM you if they have the wrong book, and NOT to mark it received, or rWAp. Give them each 1 credit, to mail the books to each other. Don't refund their credit. Each person marks their books received when they get the correct book.  You will get your 2 credits for mailing the books, but you will be out 2 credits to cover the  extra postage for your receivers.

I would do what Sara suggests IF they both agree to that.  Since mailing each book will probably cost more than the cost of a credit ($2 in the Book Bazaar), I wouldn't be happy with that solution if I were one of the receivers.  I personally would want the postage amount in PayPal funds, but only because I'm ridiculously poor.  Just give them a heads up, have them notify you once they receive your book, and see what they say.  Good luck!

What Sara said   let the two know there might be a problem, and if so to not mark the books received until they actually receive the correct book.  Hopefully if there's a problem the receivers will be willing to forward the books for you.

There's instructions on this procedure in the Help Documents, but Sara covered it quite well.