Google Stock Falls as Share Total Doubles  SAN FRANCISCO (Reuters) - Shares of Google Inc. &lt;A HREF="http://www.investor.reuters.com/FullQuote.aspx?ticker=GOOG.O target=/stocks/quickinfo/fullquote"&gt;GOOG.O&lt;/A&gt;  fell as much as 6.5 percent on Tuesday, as selling restrictions  were lifted on 39 million shares held by employees and early  investors in the newly public Web search company.