I have similar examples in my experience. If you run operations it is something you need to watch out for because, in my experience, every vendor extends feelers to see if this is a possibility. It goes unnoticed by accounts receivable because the vendor marks the price up with the 'extra' so they see an invoice, and pay it and get the equipment, none the wiser that is some % higher than it "could" be. This is amplified by vendors of IT gear that quote a "high" MSRP, and then offer a big discount. So the vendor has rack switches for $4500 MSRP they are selling you for $3000 when the 'standard' discount would be $2500 (45 points off list). The accountant sees the 33% off list so they are happy, the vendor gets more than they need to make their margin, and the IT guy on the inside manages to pocket a few thousand that arrives via a side channel.

Everyone gets a little something and everyone is happy as a clam. It is fairly insidious and difficult to combat unless you can pit distributors against each other or vendors in order to force out what their real bottom line is.