yes, you can possibly spread the virus over and over again them multiplying even more, getting both sicker and resistant to drugs, always use a condom(unless you are trying to concieve, but dont try if you have HIV!)
Even if both people in a sexual relationship have HIV, it is still important to use a condom. HIV mutates and without using a condom, you are likely to pass different HIV mutations back and forth, making each other more sick.
