aakk9999 - 4:59 pm on Oct 15, 2011 (gmt 0)
OK, I think I got it.
So you had this: example.com/productx/cat/124 as internal links and anything else with "124" did 301 to example.com/productx/cat/124 (which is the right way to do it)
The example.com/productx/cat/124 URL format was indexed.
Now the character was removed and it affected both, your internal links AND your redirect.
So, lets say that for example, the character removed was x from "productx". Hence now internal links are in the format of example.com/product/cat/124 and also any other format of URL with "124" now redirect to this new version of URL. Consequently, all your "old" links would automatically redirect to the new URL format.
As you say, when the mistake was made, all internal links also took the format of the "new URLs".
Here is how Google saw it:
- It knows of nnn links in the "old format" and these are the links it has found on the site before.
- Suddenly, it recrawls the site and it finds zzz "new" links and the old links are not there (as your old links are now replaced with "new format"). Even though it did not find "old" links any more, it will hang onto them in index as it knows they exist(ed) - until it recrawls them.
- In most cases, Google is quicker to crawl new links than to re-crawl existing. It is likely that looking at crawl activity in WMT you will find a spike in crawl which will correspond with when Google hit the site and suddenly found many "new" links.
- So, Google found many links with a new link format, but has not re-crawled old link format yet (hence it is not yet seeing 301 redirect from old to new).
This is the cause of your "duplicate titles" in WMT.
Tedster and seoskunk both think you should revert back as soon as possible. I think the same.
I would bite the bullet and revert. Then wait until Google sort itself out. If this is one-off mistake (i.e. the site was stable with regards to links before), and providing you get "reversion" correct, you should see the full recovery within certain time (month to three months usually, depending on crawl rate etc.).