Exception raised after clicking for the second time on the save button of the job apply form

As for the first time I had no sign for being sure my form had been saved , I just retried again and here what I had in the console:

2009-01-13 15:14:58,265: ERROR [org.jahia.ajax.gwt.filemanagement.server.helper.FileManagerWorker] - Error when calling CaptchaService
com.octo.captcha.service.CaptchaServiceException: Invalid ID, could not validate unexisting or already validated captcha
at com.octo.captcha.service.AbstractCaptchaService.validateResponseForID(AbstractCaptchaService.java:146)
at com.octo.captcha.service.AbstractManageableCaptchaService.validateResponseForID(AbstractManageableCaptchaService.java:367)
at org.jahia.ajax.gwt.filemanagement.server.helper.FileManagerWorker.checkCaptcha(FileManagerWorker.java:1176)
at org.jahia.ajax.gwt.filemanagement.server.JahiaNodeServiceImpl.createNode(JahiaNodeServiceImpl.java:145)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:585)
at com.google.gwt.user.server.rpc.RPC.invokeAndEncodeResponse(RPC.java:527)
at com.google.gwt.user.server.rpc.RemoteServiceServlet.processCall(RemoteServiceServlet.java:164)
at com.google.gwt.user.server.rpc.RemoteServiceServlet.doPost(RemoteServiceServlet.java:86)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:637)
at org.jahia.ajax.gwt.commons.server.AbstractJahiaGWTServiceImpl.service(AbstractJahiaGWTServiceImpl.java:59)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
at org.jahia.ajax.gwt.commons.server.AbstractJahiaGWTServiceImpl.service(AbstractJahiaGWTServiceImpl.java:65)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.jahia.bin.filters.jcr.JcrSessionFilter.doFilter(JcrSessionFilter.java:23)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.tuckey.web.filters.urlrewrite.RuleChain.handleRewrite(RuleChain.java:164)
at org.tuckey.web.filters.urlrewrite.RuleChain.doRules(RuleChain.java:141)
at org.tuckey.web.filters.urlrewrite.UrlRewriter.processRequest(UrlRewriter.java:90)
at org.tuckey.web.filters.urlrewrite.UrlRewriteFilter.doFilter(UrlRewriteFilter.java:417)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:233)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:433)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:128)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:568)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:286)
at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:845)
at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:583)
at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:447)
at java.lang.Thread.run(Thread.java:595)