I am totally confused-  I was just checking my custom dc's and noticed that the last one I did is listed twice... weird thing is I only printed it out once and the 2 listings show different dc #'s... to the same person...  I was also charged twice.  ???

hmmm sounds weird. You can check your money registry to see if you were charged twice.

Ouch, sounds like -- for whatever reason -- the browser submitted the info twice and resulted in two transactions. You could contact the PBS staff, but I believe they're unable to process refunds on DC's. :(

can I reprint the label with the dc I don't use this time and use it in the future to mail to that person (we both play in swaps, so it is likely I will send her a book in the future)

According to the help docs for custom DC you can reprint within the next 14 days. So I suggest printing it again and saving the PDF file.