Only under extreme conditions. 
 
More seriously - I had one very similar case.  Working for Bankers Trust investment bank;  whole team went to LA to conference with American cousins.  Shared rooms ( gender segregation).  Wasn't a preferred thing, but we simply choose a mate/ friend to share with.   Bosses got their own rooms.  Some pretty big egos there, but it was "whatever - just show me the bonus" 

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As another example, international cricketers and Olympic athletes  always share rooms.
I'm not sure what the "obvious reason" would be in the OP for always separate rooms in MNC - but it doesn't sound very savoury.