See issue #4062. When calculating an array formula, populate all the cells associated with the result. This is almost the same as Excel's behavior. As yet, there is no attempt to create a #SPILL error, so cells may be inappropriately overwritten. Also, if the array size shrinks (e.g. there are fewer unique values than before), no attempt is made to unpopulate the cells which were in range but are now outside the new dimensions. Spill and unpopulation are somewhat related, and will probably be handled at the same time, but their time has not yet come.
UNIQUE, at least for rows, was treating all cell (calculated) values as strings. This is not the same behavior as Excel, which will preserve datatypes, and treat int 3 and string 3 as unique values. Excel will, however, treat int 3 and float 3.0 as non-unique. Within UNIQUE, private function uniqueByRow is changed to try to preserve the the datatype when executing (it will probably treat 3.0 as int - I don't know how I can, or even if I should attempt to, do better - but no int nor float should be treated as a string).
oleibman