Planned Order showing different supplier other than sourcing rule existed one

Summary:

In Supplies Demand Table, Planned order suggested/Showing a Supplier which doesn't existed for that Item. We are using category based Sourcing rule. The item associated to BLATCHFORD Supplier Sourcing rule, But out 13 lines, Only one Showing 3-POINT Supplier. This item doesn't have associated to this sourcing rule.
Can you please suggest what could be the reason for this strange one.

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