Tesla K80 and OpenCL - opencl

Question

I have an Nvidia Tesla K80 sitting in a LINUX box. I know that internally a Tesla K80 has two GPUs. When I ran a OpenCL program on that machine, looping over all the devices, I get to see four devices (4 Tesla K80s). Would you know why this could be happening?
Here is the host code:
ret = clGetPlatformIDs(0, NULL, &platformCount); openclCheck(ret);
platforms = (cl_platform_id*) malloc(sizeof(cl_platform_id) * platformCount);
ret = clGetPlatformIDs(platformCount, platforms, NULL); openclCheck(ret);
printf("Detect %d platform available.\n",platformCount);
for (unsigned int i= 0; i < platformCount; i++) {
// get all devices
ret = clGetDeviceIDs(platforms[i], CL_DEVICE_TYPE_GPU, 0, NULL, &deviceCount); openclCheck(ret)
devices = (cl_device_id*) malloc(sizeof(cl_device_id) * deviceCount);
ret = clGetDeviceIDs(platforms[i], CL_DEVICE_TYPE_GPU, deviceCount, devices, NULL); openclCheck(ret)
printf("Platform %d. %d device available.\n", i+1, deviceCount );
// for each device print critical attributes
for (unsigned int j = 0; j < deviceCount; j++) {
// print device name
ret = clGetDeviceInfo(devices[j], CL_DEVICE_NAME, 0, NULL, &valueSize); openclCheck(ret)
value = (char*) malloc(valueSize);
ret = clGetDeviceInfo(devices[j], CL_DEVICE_NAME, valueSize, value, NULL); openclCheck(ret)
printf("\t%d. Device: %s\n", j+1, value);
free(value);
//more code here to print device attributes
Here is the output:
Detect 1 platform available.
Platform 1. 4 device available.
1. Device: Tesla K80
1.1 Hardware version: OpenCL 1.2 CUDA
1.2 Software version: 352.79
1.3 OpenCL C version: OpenCL C 1.2
1.4 Parallel compute units: 13
2. Device: Tesla K80
2.1 Hardware version: OpenCL 1.2 CUDA
2.2 Software version: 352.79
2.3 OpenCL C version: OpenCL C 1.2
2.4 Parallel compute units: 13
3. Device: Tesla K80
3.1 Hardware version: OpenCL 1.2 CUDA
3.2 Software version: 352.79
3.3 OpenCL C version: OpenCL C 1.2
3.4 Parallel compute units: 13
4. Device: Tesla K80
4.1 Hardware version: OpenCL 1.2 CUDA
4.2 Software version: 352.79
4.3 OpenCL C version: OpenCL C 1.2
4.4 Parallel compute units: 13

Answer 1

Most probably 2 are 32-bit implementations, 2 are 64-bit implementations from multiple drivers. Maybe old drivers needs to be cleansed by some display driver uninstaller software. Check bitness of each device implementation please.
Or, there are virtual gpu(GRID?) services left active causing duplicated devices so maybe you can deactivate virtual gpu to solve this.