Personal information of some of the hundreds of thousands of licensed professionals potentially exposed in a breach of a Washington state database may already have shown up on “dark web” clearinghouses used by identity thieves. State investigators haven’t said whether Social Security numbers and other personal data were actually stolen from a database of more than 250,000 professional and business licensees used by the state Department of Licensing, agency officials said. The database is maintained by Salesforce, a San Francisco software company. But two individuals who previously had a busine…