*Does the effect of BW- Sirroco the Dawn stacks each turn it is activated in one monster?

*If I have 2 BW- Sirroco The Dawn in the field and choose to activate their effects on my face up BW- Bora the Spear, how much atk will be gained by BW- Bora the Spear?

*Also, does the effect of BW- Sirroco The Dawn is permanent?

>.<

Here's the answer to your questions, in the order that they were asked. At least this is how I interpretted your questions.

1. No the effect of BW Sirocco will not stack between turns.

2. The effect WILL stack in this situation, as they're both effects that increase attack, and will not interfere with each other as they're added to the current attack and not the original attack. (at least to the best of my knowledge).

3. The official ruling found here is that the effect ends at the end of the turn it is applied.

Oh so that's it. BW- Sirroco the dawn don't tell that his effect will only last for that turn. Thanks for that! ^^