On the first time installing the newest Intel CL Runtime, it erases the nvopencl/amdcl entries. If you had 16.2 installed, it doesn't delete the entry so you end up with duplicated opencl devices, though it replaces the runtime in Programs and Features. uninstalling 16.2 also does not remove the intelopencl entries so you must remove these manually to install 18.1 clean. (16 uses intelopencl**.dll, 18 uses intelocl**.dll) Installing 18.1 a second time (after uninstalling) does not remove the Nvidia / AMD opencl entries. Both behaviors occured on 2 machines, and another user also confirmed the first behavior from a clean install having never had 16.2 installed.