What you need to do is edit your config file to not include Mulitiviews in your document directories. The config file will vary according to which specific virtual servers and/or user directories you need to modify. For the default server, open /etc/apache2/sites-available/default in gedit (or any other text editor) and remove the reference to Multiviews from the default document directory section. You'll need the sudo command for root access.
sudo gedit /etc/apache2/sites-available/default
For reference, here is part of my config file on my development box:
Options Indexes FollowSymLinks MultiViews
allow from all
Remove any Options you don't want from the Options line, save the file and issue the restart command:
sudo apache2ctl restart