It will erase your Tetris save yes. But you can backup the save if you want to use it again at a later date.I have a question-
I have my Tetris DS saves on a DS cart (64k) and that's been working great. If I do the same for this ROM onto the same cart, with it erase my previous Tetris save? Do I need to track down another 64k cart to save?
You can do this with Rein or ETool apps, they both work fine for me. ReinMoon ver0.2 beta has a save manager aswell.
And double lol @ that request