It looks like mod_mono.so is loaded twice ...
grep -ri "LoadModule" /etc/apache2 | grep mono
/etc/apache2/mods-available/mod_mono.load:LoadModule mono_module /usr/lib/apache2/modules/mod_mono.so /etc/apache2/mods-available/mod_mono_auto.load: LoadModule mono_module /usr/lib/apache2/modules/mod_mono.so
then a2dismod mod_mono_auto
service apache2 restart
It looks like mod_mono.so is loaded twice ...
grep -ri "LoadModule" /etc/apache2 | grep mono
/etc/apache2/ mods-available/ mod_mono. load:LoadModule mono_module /usr/lib/ apache2/ modules/ mod_mono. so mods-available/ mod_mono_ auto.load: LoadModule mono_module /usr/lib/ apache2/ modules/ mod_mono. so
/etc/apache2/
then
a2dismod mod_mono_auto
service apache2 restart