W/O having had any look into the code I would assume that your's case statement is (as it should) be complete in itself, i.e. all conditions are covered by their own "when xyz =>" statement. Thus the "when others =>" never get's active and is thus removed by the compiler, also removing the not allowed two driver for one signal condition... If this is a correct assumption, remove the "when others" and replace the last when condition by when others (thus the when others condition is a valid one). This modification should bring up the error message of two drivers for one signal :-)
