Can I include two jsp:plugin actions on one JSP page? It does not compile under Tomcat.

Yes. Just include an extra set of {}'s around the plugin code:

<% { %>
<jsp:plugin 
  type="applet" 
  code="Clock2.class"
  codebase="/examples/jsp/plugin/applet"
  jreversion="1.2" 
  width="160" 
  height="150" >
    <jsp:fallback>
        Plugin tag not supported.
    </jsp:fallback>
</jsp:plugin>
<% } %>
<% { %>
<jsp:plugin 
  type="applet" 
  code="Clock2.class"
  codebase="/examples/jsp/plugin/applet"
  jreversion="1.2" 
  width="160" 
  height="150" >
    <jsp:fallback>
        Plugin tag not supported.
    </jsp:fallback>
</jsp:plugin>
<% } %>