If you have one of the unlimited pledges ($100 or $250), then YES. By pledging an additional amount equal to your base pledge level you will receive another copy of the base game and all associated stretch goals.
If you have one of the limited pledges ($220 to $245), then NO. Backers with those pledges can only get 1 copy of the pledge at that cost and with that delivery time. They can, however, get extra copies of the unlimited $250 R'lyeh Rising pledge, which will be delivered later.