Two simultaneous AbstractMainWindow

Hi, i have created dynamic form which is avaliable for users of our domain in iframe as part of our crm system. User is signed via link and redirected to custom AbstractMainWindow. Problem is that if user after opening iframe opens regular application he gets following exception.

How can i solve this?

java.lang.ClassCastException: class com.company.doprava.web.screens.Manager cannot be cast to class com.company.doprava.web.screens.Manager (com.company.doprava.web.screens.Manager is in unnamed module of loader com.haulmont.cuba.core.sys.javacl.JavaClassLoader$FileClassLoader @95ab2a9; com.company.doprava.web.screens.Manager is in unnamed module of loader org.apache.catalina.loader.ParallelWebappClassLoader @1c55f277)
	at com.company.doprava.web.ManagerLinkHandler.handle(ManagerLinkHandler.java:69)
	at com.haulmont.cuba.web.AppUI.processLinkHandlerRequest(AppUI.java:679)
	at com.haulmont.cuba.web.AppUI.processExternalLink(AppUI.java:651)
	at com.haulmont.cuba.web.AppUI.handleRequest(AppUI.java:572)
	at com.vaadin.server.communication.UIInitHandler.reinitUI(UIInitHandler.java:262)
	at com.vaadin.server.communication.UIInitHandler.getBrowserDetailsUI(UIInitHandler.java:162)
	at com.vaadin.server.communication.UIInitHandler.synchronizedHandleRequest(UIInitHandler.java:67)
	at com.vaadin.server.SynchronizedRequestHandler.handleRequest(SynchronizedRequestHandler.java:40)
	at com.vaadin.server.VaadinService.handleRequest(VaadinService.java:1578)
	at com.vaadin.server.VaadinServlet.service(VaadinServlet.java:425)
	at com.haulmont.cuba.web.sys.CubaApplicationServlet.serviceAppRequest(CubaApplicationServlet.java:329)
	at com.haulmont.cuba.web.sys.CubaApplicationServlet.service(CubaApplicationServlet.java:215)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:741)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:231)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
	at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
	at org.springframework.web.filter.CompositeFilter$VirtualFilterChain.doFilter(CompositeFilter.java:108)
	at org.springframework.web.filter.CompositeFilter.doFilter(CompositeFilter.java:74)
	at com.haulmont.cuba.web.sys.CubaHttpFilter.doFilter(CubaHttpFilter.java:93)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
	at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:202)
	at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:96)
	at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:526)
	at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:139)
	at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:92)
	at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:678)
	at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:74)
	at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:343)
	at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:408)
	at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:66)
	at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:861)
	at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1579)
	at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49)
	at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1128)
	at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:628)
	at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
	at java.base/java.lang.Thread.run(Thread.java:834)