Approve "My Staff Tasks" function does not work when "My Staff" person is lised as approver multiple

Summary:

Approve "My Staff Tasks" function does not work when "My Staff" person is lised as approver multiple time.

Is this by design?

Content (required):

We have set po change approval rules as follows.

Rule1: When line change amount is over 10,000 USD, set approvers up to Job Level 4.

Rule2: When line change amount is equal or less than 10, 000 USD, set approvers up to Job Level 3.

And when creating a change PO having line1 change amount is less than 10,000 USD and line2 change amount is over 10,000 USD, system creates approver list as follows.

1. Job Level 1 user
2. Job Level 2 user
3. Job Level 3 user