Issue with High Density bots when running IE based automation

I configured a Win 2012 R2 server for HD bots as per UiPath documentation - Installed 2 bots and configured to run both in parallel against 2 user IDs. Both these processes launch a java application via a browser. When I run these 2 processes in parallel and the 2nd bot starts, the 1st bot fails with “Unable to communicate with Internet explorer” error and eventually the 2nd bot also fails. Has anyone used high density bot for long running IE based processes ?