Question about Dragon Age Origins?

I know this game is pretty old now, and Dragon age 2 is coming out real soon, but I have a question about it. I want to get the perfectionist achievement, which is when you have to discover all endings on all playthroughs. I played this game once, got the ending where I sacrifice myself and then reloaded the save and accepted morrigans offer. So in one playthrough I got two of the endings. On the next playthrough, I had Alistair sacrifice himself, which was another ending. Now, All I need is to have Logain sacrifice himself. However, I was wondering, if I deleted my first playthrough (the one were I got the "ultimate sacrifice" and "a dark promise" achievement), will I still be able to get the prefectionist achievement?? Please help, I want that achievement.