It can be redirected. However, you need to determine how to discern the clients to determine which is redirected to pacfile A or B.
There are several methods that come to mind
Method 1) You could write up an irule that looks at the IP address of the client and redirects to Pacfile A on ODD IP numbered clients and Pacfile B on even numbered clients. It won't guarantee evenness but it might be close depending on how your clients are split up.
Method 2) Create 2 Virtual addresses 2 virtual address that can host http://proxycfg.abcd.com/proxy/cfg.proxy. One VS redirects to pacfile A and the other to pacfile B. Then create in your DNS a round robin entry for proxycfg.abcd.com.
Method 3) Create irule where you identify several subnets you want to go to redirect to pacfile A and other subnets to pacfile B
thoughts?
Bhattman