Workflow for PO signature: Duplicated workflow records and emails

SOLVED

Hi all,

May I ask you for advice regarding this case? 

I'm setting up PO signature workflow in Sage X3 PU9 patch 6. When I tries creating a PO, the system creates duplicated workflow records and sends duplicated emails as below.

At Workflow monitor:

Emails received:

The POHSIG workflow rule I take from default X3 folder. I only change the User assignment as below:

I don't know what is the possible cause for duplicated records and emails as above. I'd appreciate your insight and support.