Whoa, whoa, whoa!!! Double Summon just lets you NORMAL SUMMON twice in the turn u play it. So u can summon 2 Lv 4 or below monsters, or summon a lv 4 or below and tribute it for a lv 5 or 6. Normal summons are FROM UR HAND and you still have to sacrifice to summon lv 5+ monsters.
Unless a card itself or another effect specifically says otherwise (or it's just common sense like Fusions and Synchros), then Normal and Special Summons can only be from your hand.