I mailed two packages at the same time, both with delivery confirmation from PBS and metered postage from my work. This is the way I have done it since I started using PBS and I have never had  single problem. Today I got both packages back saying insufficient postage telling me that the DC fee was .80. Should I just try mailing them again at a different post office? I don't want to pay the extra when I know I don't have to. Any advice?

If at all possible, take them into the post office and ask for answers.  If you used media Mail rate plus .19 for the DC the books should have gone.  USPS appears to be reorganizing, and we're hearing of quite a few errors.  So ask your PO, and if the error was theirs the books should be re-mailed with no further expense to you.

Preprinted DC frequently seems to be an issue, no idea why - as PBS, e-bay, and paypal all have the same format.  But many postal employees are uninformed and undereducated in this area.  Appears your books may have encountered a trainee 

I agree with Denise - head to your PO and ask them for some answers.   With the cutbacks I have encounterd many uneducated postal workers and postmasters!

Yes, please do go to the the PO or call the hot line.  It's always been resolved when I've done this, but it has happened to me so many times I've given up.  The problem is  a sorting center a few hours from here.  If the books don't go through there, the DC is fine.  About 1/2 that I sent through there w/ just DC come back if  I use stamps or metered postage.  The all online postage from PBS or paypal goes through fine. 

I hope you have better luck than I did.  The local PO and the hotline are great whenever it happens, but it must be a cultural thing at this center, since the books would just be returned again.  At least my complaints are on file, and maybe help someone else out.  The hassle just became not worth the benifit for me.