As stated by Google AdSense, it is possible to have non-Google ads displayed along with Google ads.
You can run all of our ad formats on the same page with AdSense. Our ad scripts are fully compatible with other ad networks.
In addition, you do not need to replace any existing ads/network/provider you currently have. PurpleAds works independently and is totally separated.
Read more here on Using other ad networks together with AdSense