While having one antivirus program is a must for every computer to stay protected against various kinds of malware and viruses, using two is strongly not recommended.
There are several reasons why: the two antivirus programs running together could slow down your computer, they might identify each other as a virus, they will try either to block or kill each other, they will fight over viruses found, etc. It could lead to file corruption or other conflicts and errors that make your antivirus protection less effective or nor effective at all.
If you wish to download adaware antivirus 12 and already have another antivirus software installed on your PC, we strongly recommend to remove or at least disable the other antivirus as it can cause a conflict.
If you don't want to remove/disable another antivirus program installed on your PC, you have an option to install adaware antivirus 12 as a second line of defense (installation in a compatible mode) where no drivers will be installed. If any adaware antivirus drivers were installed earlier, they are removed. It allows you to use the Scan Computer option only. Please remember, if one or more incompatible antivirus programs are installed on your PC, running these programs alongside with adaware antivirus may generate conflicts and errors.