Assuming Bogos, not CC certs or the intothenights free nights certs

Well IHG t+c's say not transferrable, but there is no serial numbers etc on supplied bogo certs so in practise yes,

Normally one can only obtain 2x BOGOs direct from IHG, yearly Ambassador renewal + one extra if later on earning RA level.

Individual hotels can't see how many bogos a year one uses, and although I guess IHG corporate can see, there are no reports from anyone that using 4/5 bogos in a year for yourself causes any issues.