1. There are two methods for isometric graphics: the first one is 3 pixel angle (see type 1). This method uses three pixels at angles thus creating exact rectangle pleasant for eyes.

2. The second type doesn't use 3 pixels at each angle but uses one upward and two lengthwise at the whole construction (see type 2).

3. If you want to duplicate cubes of the first type, then you will get deformed cogged borders of the image, if you want to place two cubes of the first type one after another.

4. That is why the second type is recommended in case you want to duplicate cubes farther in order to create forms based on these cubes.