I think the problem is that some parts of the URL you see are not really part of the pages URL, but query string parameters, that injected into the friendly url.
I did a test and this seems to work (you do need the new beta version of the Skin object for this):
<fortyfingers:STYLEHELPER ID="STYLEHELPER5" ChangeMeta='id=MetaDescription|content=*: Page [QS:PageID]' runat="server" />
This will look for an exisitng Meta tag with id MetaDescription, and change the content attribute to:
The original Description (Represented by *) + ": Page" + the value of the PageId Query String parameter, which is 2 if your on page 2.
I set this for the articles Description in the Module: "This is my article"
The result is this description: "This is my article: Page 2" in the meta tag (if on page 2)
I used News Articles main module, should work the same for News Articles Latest
New 02.03.00 Beta version of skin object here: http://stylehelper.codeplex.com/releases/view/79650
I tested this on DNN 5.6.3