Can you tell me why.

I have around 20 Nintendo DS ROM's i kept in a folder and the mega bytes for each game is different, but now they all changed to either 16, 32, 64, or 128 megabytes. Can you tell me if this is normal because it more then doubled the size of all the total ROM's that they were before this happened.

You extracted them from the compressed archive they were stored in?

Yea but they just changed inside the folder i didn't touch them.

DS dumps are always 16, 32, 64, 128, 256, etc.That's the size they are. If they are different, then it's because they've been trimmed to be smaller, or are still compressed.

Oh thanks

The ROM images extracted from the cartridge are in powers of 2 (depending on what capacity cartridge), and the redundant data is left on. So that's generally an effective way to tell if it has been modified in some way (trimmed, patched etc.).