macOS saveAction called 2 times with notification

    -(void)mouseDown:(id)sender{
        [super mouseDown:sender];
        [super mouseUp:sender];
        [[NSNotificationCenter defaultCenter] postNotificationName:@"quickSave" object:nil userInfo:nil];
    }

    - (IBAction)saveAction:(id)sender{
        NSLog(@"Saving...");
        NSError *error = nil;
        if (![[self managedObjectContext] commitEditing]) {
            NSLog(@"%@:%@ unable to commit editing before saving", [self class], NSStringFromSelector(_cmd));
        }
        if (![[self managedObjectContext] save:&error]) {
            [[NSApplication sharedApplication] presentError:error];
        }
    }
    -(void)awakeFromNib{
        [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(saveAction:) name:@"quickSave" object:nil];
    }

Saving...
sender: NSConcreteNotification 0x101915b70 {name = quickSave}
self: <AppDelegate: 0x101927730>
Saving...
sender: NSConcreteNotification 0x101915b70 {name = quickSave}
self: <AppDelegate: 0x1005374c0>

-(void)awakeFromNib{
    [[NSNotificationCenter defaultCenter] removeObserver:self name:@"quickSave" object:nil];
    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(saveAction:) name:@"quickSave" object:nil];
}