Dll conflict caused by video games.

Hi,
I had NFS Shift 2 installed and it was working fine until I installed another game F1 2012. After installing this NFS started working slowly (unplayable), then I uninstalled F1 and it started working fine. Was this caused by dll conflicts? If not, then can two games' dlls cause conflicts? How to remove dll conflicts caused by two similar softwares?
Thank You
