when diving into "learn cocos2d game development with ios5", in ch08

in EnemyCache.m

-(id) init
{
    if ((self = [super init]))
    {
        // get any image from the Texture Atlas we're using
        CCSpriteFrame* frame = [[CCSpriteFrameCache sharedSpriteFrameCache] spriteFrameByName:@"monster-a.png"];
        batch = [CCSpriteBatchNode batchNodeWithTexture:frame.texture];
        [self addChild:batch];

        [self initEnemies];
        [self scheduleUpdate];
    }

    return self;
}

so batch is with texture "monster-a.png"

in EnemyEntity.m's initWithType method

switch (type)
{
    case EnemyTypeUFO:
        enemyFrameName = @"monster-a.png";
        bulletFrameName = @"shot-a.png";
        break;
    case EnemyTypeCruiser:
        enemyFrameName = @"monster-b.png";
        bulletFrameName = @"shot-b.png";
        shootFrequency = 1.0f;
        initialHitPoints = 3;
        break;
    case EnemyTypeBoss:
        enemyFrameName = @"monster-c.png";
        bulletFrameName = @"shot-c.png";
        shootFrequency = 2.0f;
        initialHitPoints = 15;
        break;

    default:
        [NSException exceptionWithName:@"EnemyEntity Exception" reason:@"unhandled enemy type" userInfo:nil];
}

if ((self = [super initWithSpriteFrameName:enemyFrameName]))
{
    //...
}

so the returned object may be in 3 different frame. since Only the CCSprites that are contained in that texture can be added to the CCSpriteBatchNode, obviously, 'monster-b.png' is not contained in 'monster-a.png', why the different enemy can still be added to the batch?