Cross-reference - a fix! and also Why?

Raising a PO against vendor xyz for part #1 and we got this:

Turns out there was a vendor part reference elsewhere causing this but that reference was for vendor abc for part #2 referencing part#1.

Is there a way to turn this off? Just wondering why this would kick in if we’re doing a PO against xyz and the reference was on vendor abc. Also the part for abc was part #2 which seemed the opposite of what it should be compared to the screenshot. So to track this down I did a BAQ against PartXRefVend with a join on vendor to show the vendor ID. Then used supplier price list to track down part#2

After all that this reference seems legitimate so I suspect some issue happened in the past with part numbers that still hasn’t been cleared up. We are using supplier part# from supplier price list to show on the PO if there is a vendor partnum.