No, pasting a new entry over old microfilm or microfiche isn't quite comparable to Elvis still being alive or the feds staging a moon landing. (Just to make it clear to you, curiosity, no one on FR that I know of endorses either of the latter two theories.)
The perps need not go to every library that maintains microfilm (or microfiche) from the Honolulu Avertiser from August 1961. (The number of such libraries is, BTW, probably much smaller than you think. Given Hawaii's relative geographic isolation from the mainland, interest in Hawaii newspaper archives is generally quite minimal elsewhere in the country - this controversy the exception to to the rule.) Access to only one such library or to the respective newspaper archives would suffice to produce an altered product whose image could then be produced on a pro-Obama web site. Furthermore, as others have pointed out, the absence of the birth announcement for the Nordyke twins in either of the posted newspaper Birth Announcement columns is consistent with alterations of the originals, assuming that all births filed with the Hawaii DOH over the week preceding the publishing of the announcements were published as a matter of policy.
I would suspect that only the main Honolulu Public Library and the Newspaper's Office itself would archive paper copies of back issues.
The perps need not go to every library that maintains microfilm (or microfiche) from the Honolulu Avertiser from August 1961.
Well, if they didn't, then it would be pretty easy to detect their fraud, wouldn't it? Birthers are scattered accross the country. I find it very hard to believe that some birther living near a library with the fiche or film hasn't gone to check it out.
Given Hawaii's relative geographic isolation from the mainland, interest in Hawaii newspaper archives is generally quite minimal elsewhere in the country - this controversy the exception to to the rule
Big city and university libraries will often keep microfilms of even obscure publications. The New York Public library, for example, has all the issues going back to 1959:
http://catalog.nypl.org/iii/encore/record/C%7CRb12638522%7CShonolulu+advertiser%7CFf%3Afacetmediatype%3Ah%3Ah%3AMICROFORM%3A%3A%7CP0%2C2%7COrightresult?lang=eng&suite=pearl
I'm sure there must be at least one birther who can easily access the New York Public Library. With a little more searching on worldcat, I'm sure you'll find other libraries that have it. I would be really surprised if the Library of Congress didn't have it
Furthermore, as others have pointed out, the absence of the birth announcement for the Nordyke twins in either of the posted newspaper Birth Announcement columns is consistent with alterations of the originals,
I'm not so sure the twins' announcement is absent from the paper. Just because their birth isn't announced on the same page as Obama's, or even in the same issue, doesn't mean it wasn't announced. It could be on the next page. Alternatively, it's possible that the data from the health department came in too late to make that issue's deadline, in which case it would be in the next issue that published birth announcements.
I have yet to see a report from anyone who has gone and searched the next page on microfilm or microfiche and the next issue with birth announcements. Have you?