I am working on an Excel Add-in, and requirement was to copy one entire column and paste to some new location. I used range.copyFrom() function to copy, but it was not copying all formulas correctly. If Address of a cell referenced in formula is written as C$1 or C1 and new paste location is 2 columns right to original cell, then formula is updated to E$1 or E1, which is as per expectation. However if address is written as $C1 then it remains $C1 in new column instead of $E1.
After that I manually tried to copy column and its behavior was same. So if a cell address is referred as $C1 then either Excel should not accept it as valid cell or it should also update this format address in pasted formulas also.