A preconceived notion tricked my aging eyes

As you know things burn out and even blow up when the devices intermix.
True for the most part but I wonder sometimes.

I was working as a young engineer for the worlds largest mfgr of refrigerated
machinery.
I was a regional operations
manager meaning I was in the field hands on addressing and correcting problems
that occur when things get misapplied. Well we shipped 230 volt equipment to a
big customer with a 206 volt supply and the in house engineers caught the application
and demanded we replace the compressor and components.
Well we did to set it right. And I am sure that for the most part that the
machinery would of failed in it's expected life cycle.

So last year I am working on a piece of equipment brought into the US
from Brasil.
It had been running
for a customer for years. Very old equipment.
Original OEM components.
and I said hey you can't do that and the new owner replied that his friend
had it running for years.
Well I put my amp reader on it and jumped . I saw 11 amps where
I was expecting 4 to 5 amps tops and said this couldn't be and
told him we couldn't install the second piece on the same incoming power
supply due to overloading the
circuit and proceeded to suggest replacing the compressor.

He was addimit that this worked for years on the same type of circuit.
So we disagreed and I left thinking we could talk again.
I came back and everything was in and in fact running well.
He had wired the other in anyways and it was working. I was puzzled so
I started over in my analysis of the field data.

I found that the compressor was actually running at 1.8 amps and my
preconceived notion tricked my aging eyes and loss of sight to believe that this
was 11 amps. Hmmm so what do you think about this observation?
This is heavy rugged forgiving equipment.
Not fragile
components like electronics. So any ideas as to why this was so?

It may of been that the compressor was worn and not compressing to the top of the dome of the compression cycle and basically running lightly loaded?
It could be that the charge was low and the cycle again low in back pressure to head pressure ratio. So the amps should of been really around 4 amps. But why didn't the motor burn up due to the miss application of electrical hz?