According to BPMN 2.0 specification (see quote below) it is possible to create processes where Start Event has more than one outgoing Sequence flow like on screenshot.

When the trigger for a Start Event occurs, a new Process will be instantiated and a token will be generated for each outgoing Sequence Flow from that Event.

This behavior also supported by jBPM Engine if you start Application server with jbpm.enable.multi.con property.

Example for Wildfly Application Server: ./standalone.sh -Djbpm.enable.multi.con=true

But this type of processes is not supported by Stunner Designer.