I think something went wrong when you exported and imported the database. (I assume that's how you got the two sites up at the same time?) MediaWiki always stores all text in the UTF-8 encoding, and in the database, the encoding of the fields is marker as either "binary" or "utf8" (the former is recommended due to problems with older MySQL versions).
My guess is that in the `page` table, the `page_title` field was marked as being in some different encoding. This does not normally cause problems (MediaWiki doesn't use any of MySQL encoding conversion functions), but when you exported it, MySQL tried to interpret the UTF-8 bytes as whatever-encoding bytes and converted that to UTF-8. When you imported, the data was already damaged.
If that's indeed the case (I'm just guessing), change the encoding of the field in the original table (do not convert or re-encode the data, it's correct, just marked wrong) and try to re-export and re-import that table.