NICs with the same MAC on one switch

Hi all,
Presuming that we connect 2 NICs with the same MAC to one switch (port1 and port2), what would a switch handle such condition? Will the MAC table be messed up?
Actually, in a cloud computing environment, different VMs from different customer might connect with the same virtual switch and both VM could have the same MAC and/or IP address.
I just wondering how could a switch handle this.
thank you!

Alain's answer is a good one..
It breaks the fundamentals of switching to have TWO separate physical ports registering the same MAC address in the CAM table. As he mentioned, the switch would have to constantly rewrite the CAM entry each time a frame appears from a different physical interface.
If the two identical MAC addresses appeared on the same physical port, that does not break any "rules" of switching - all you would see is 1 entry in the switch for that physical interface.
As for your follow-up question regarding the cloud environment. I can't say I have any experience in that type of environment, but I would say that Private VLANs might be one of the potential answers.

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