Hi Brannon
When you first setup your Ledger in ACCPAC Plus and/or Adagio, you have a choice of a 12 or 13month Fiscal Calendar.
Some companies use a 13th Fiscal period for various reasons to do with adjustment entries or to compensate for how many days in a month they actually use for their fiscal period 'cut off'.
I'll bet this is explained better, and in more detail by your Accountant, or in the manual that comes with the Ledger program you are now using.
Regards