How to bind two NSTextField instances to one NSString member

AppDelegate.m

@implementation AppDelegate

@synthesize window = _window;
@synthesize textField1 = m_textField1;
@synthesize textField2 = m_textField2;
@synthesize foo = m_foo;

- (id)init {
    self = [super init];
    if (self) {
		m_foo = @"Init";
	}
    return self;
}

- (void)awakeFromNib {
	assert(m_textField1);
	assert(m_textField2);

	NSDictionary* textFieldBindingOptions = [NSDictionary dictionaryWithObjectsAndKeys:
					        [NSNumber numberWithBool:YES], NSValidatesImmediatelyBindingOption,
					        [NSNumber numberWithBool:YES], NSContinuouslyUpdatesValueBindingOption,
					        nil];

	[m_textField1 bind:@"value" toObject:self withKeyPath:@"foo" options:textFieldBindingOptions];
	[m_textField2 bind:@"value" toObject:self withKeyPath:@"foo" options:textFieldBindingOptions];
}

@end