Possible unintended duplicated token

I’m completely new to BPMN modelling so I’m learning from existing examples.
I have a question regarding this section of a subprocess.

The user task “KYC Accounts” is set as a sequential multi instance.
The interrupting boundary conditional event is checking if a variable called “goBack” is true.

When this variable is set to true, what is happening to the multiple instances of the user task ?
Are they all interrupted or only one of them ?
In case only the actual instance is interrupted, could the token on the user task be splitted with one going back to the previous user task and one going out to the end event when all the instances have been completed by the user ?

Thank you to whom is so patient to answer to such a basic question.
Have a great day

Hi @mfmanca,

All instances are interrupted.
If this is not the intended behavior then the “KYC Accounts” task can be embedded within a multi-instance sub-process and boundary event to be attached to the task (a simplified working example is attached).
multi-instance-boundary-event-v2.bpmn (7.0 KB)