Requistion Approval Workflow - Is this normal?

We noticed some weirdness with the requisition approval workflow. The approval goes up the chain and gets to Approver1 who has an unlimited approval amount. The amount is 500K on the req. Approver1 has no supervisor defined. Approver1 approves and then it inexplicably goes to Approver2 who has a 250K limit and requests his approval. He approves and that completes the workflow. So the question is, why would it go to Approver2 at all when Approver1 had the unlimited approval amount ability and Approver2 is limited to 250K? Did this quirk occur because Approver1 has no supervisor defined?