[GSS](6.4.z) Copy&Paste activities between different processes does not work properly in BPM Suite 6.4.x

Although it is possible to copy/paste nodes between different process instances, it does not work properly. Simple test case, which is to copy one task (t1) from one process (p1) to another process (p2), seems to work ok. However if you try to copy a second task (t2) from the second process (p2) into a third one (p3) the task that gets copied is the first one (t1). It is only possible to copy a other node when reseting all perspective ("+" button).