Effect Stacking

What is the verdict about this:

Use an effect monster that selects a monter 'That monster card can attack twice during each battle phase'

Use a trap that "Select 1 Level 8 monster you control. During this turn, the selected monster can attack twice."

Have a feeling that using both on the same monster is just a waste of an effect but twas an idea i had thats all

Na it wont stack. The wording on them both says the monster can attack twice. If one for example said "select one monster, that monster may have an additional attack this battle phase" perhaps it might.