Mail merge page numbering in Word 2010 and printing same

Did you use { SECTIONPAGES } instead of { NUMPAGES } for the 11?

What field construction are you using in the footer?

It should be { Page } of { Sectionpages } - assuming a document with one section per record, which should restart the page count for each record when merging to a new document.

With respect to the double sided printing, you should treat each record as a separate print task (again assuming one section per record).

You could use a macro e.g. Sub SplitMergeLetterToPrinter()
Dim Letters As Long
Dim Counter As Long
Letters = ActiveDocument.Sections.Count
Counter = 1
While Counter < Letters
    ActiveDocument.PrintOut Background:=False, Range:=wdPrintFromTo, _
    From:="s" & Format(Counter), to:="s" & Format(Counter)
    Counter = Counter + 1
Wend
End Sub

to split the merged document

OR

You should be OK merging to the printer with http://www.gmayor.com/ManyToOne.htm  in one to one mode (provided your data source is Excel) and if you merge to separate documents then you can use NumPages or SectionPages.