To enable the clone mode you can use the following code. It shows how to put 2 displays into clone mode:
int nNumModes;
ADLMode* pModes = NULL;
ADLDisplayMap mapArray;
ADLDisplayTarget* pDisplayTargets = NULL;
memset(&(mapArray), 0, sizeof(ADLDisplayMap));
mapArray.iNumDisplayTarget = 2;
mapArray.iDisplayMapIndex = 0;
// get current display modes
if (ADL_Display_Modes_Get(nAdapterIdx, -1, &nNumModes, &pModes) != ADL_OK)
return false;
mapArray.displayMode.iAdapterIndex = nAdapterIdx;
mapArray.displayMode.iModeFlag = pModes[0].iModeFlag;
mapArray.displayMode.iOrientation = pModes[0].iOrientation;
mapArray.displayMode.fRefreshRate = pModes[0].fRefreshRate;
mapArray.displayMode.iColourDepth = pModes[0].iColourDepth;
mapArray.displayMode.iXPos = pModes[0].iXPos;
mapArray.displayMode.iYPos = pModes[0].iYPos;
mapArray.displayMode.iXRes = pModes[0].iXRes;
mapArray.displayMode.iYRes = pModes[0].iYRes;
mapArray.iDisplayMapValue = ADL_DISPLAY_DISPLAYMAP_MANNER_CLONE;
// allocate display target for both displays
pDisplayTargets = (ADLDisplayTarget*) ADL_Alloc(2 * sizeof(ADLDisplayTarget));
memset(pDisplayTargets, 0, 2 * sizeof(ADLDisplayTarget));
pDisplayTargets[0].displayID.iDisplayLogicalAdapterIndex = nAdapterIdx;
pDisplayTargets[0].displayID.iDisplayLogicalIndex = pDspIndexList[0];
pDisplayTargets[0].iDisplayMapIndex = 0;
pDisplayTargets[1].displayID.iDisplayLogicalAdapterIndex = nAdapterIdx;
pDisplayTargets[1].displayID.iDisplayLogicalIndex = pDspIndexList[1];
pDisplayTargets[1].iDisplayMapIndex = 0;
ADL_Display_DisplayMapConfig_Set(nAdapterIdx,1,&mapArray, 2, pDisplayTargets);
ADL_Free(pDisplayTargets);
pDspIndexlist contains the iDisplayLogicalIndex of the display that can be obtained by calling ADL_Display_DisplayInfo_Get