Auto approve vs approval group within the same stage

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We have a scenario in which we have 2 business areas raising a single requisition

Line 1 for business area 1 should auto approve at the 'Header First Responder Wins' stage

Line 2 for business area 2 should go to an approval group at the 'Header first Responder Wins' Stage

Expected behaviour - line 1 auto approves, line 2 then seeks group approval

Actual behaviour - Line 1 auto approves, line 2 is then also considered auto approved because is it the same stage (first responder wins).

We have a very large number of rules and already have another set of rules sitting in the 'Header consensus' stage, so im reluctant to move re-jig the rules. But is the actual behaviour as people would expect or  should it be in line with my expectation?