CoreGraphics reports two displays connections during system wakeup

Hello,

The application I'm working on must report new hardware connections. To retrieve connected displays information and monitor new connections, I'm using the "Core Graphics" framework (see recommendation https://developer.apple.com/forums/thread/779945).
The monitoring logic relies on a callback function which invokes when the local display configuration changes(kCGDisplayAddFlag/kCGDisplayRemoveFlag).

#import <Cocoa/Cocoa.h>

static void displayChanged(CGDirectDisplayID displayID, CGDisplayChangeSummaryFlags flags, void *userInfo)
{
   uint32_t vendor = CGDisplayVendorNumber(displayID);

   if (flags & kCGDisplayAddFlag)
   {
       if (vendor == kDisplayVendorIDUnknown)
       {
           NSLog(@"I/O Kit cannot identify the monitor. kDisplayVendorIDUnknown. displayId = %u", displayID);

           return;
       }

       NSLog(@"%u connected. vendor(%u)", displayID, vendor);
   }

   if (flags & kCGDisplayRemoveFlag)
   {
        NSLog(@"%u disconnected", displayID);
   }
}

int main(int argc, const char * argv[])
{
    @autoreleasepool
    {
        CGDisplayRegisterReconfigurationCallback(displayChanged, NULL);

        NSApplicationLoad();
        CFRunLoopRun();
    }

    return 0;
}

The test environment is a Mac mini with an external display connected via HDMI. Everything works correctly until the system enters sleep mode. Upon wakeup, the app reports two displays: the first with vendor ID kDisplayVendorIDUnknown and the second with the expected vendor ID.

Why does Core Graphics report two connections during wakeup? Is there any way to avoid this?

Thank you in advance.