Can not delete pictures own size.

[slinger777]

Dear ALL!
so i got this:
Warning: rename(albums/Us_Pix/sl_us_JFK/normal_DSC00033.JPG,albums/Us_Pix/sl_us_JFK/DSC00033.JPG): File exists in f:\www\postnuke-0.726\html\modules\pncpg\coppermine\util.php on line 223s
i just need to kill original size of image. so, while i upload a pic, sometimes it has really big size, for example 3mb. and i do not need this pic any more after resizing. i wanna use just pix named _NORMAL, instead originals!!!!!
i have tried many ways to solve this problem, but.......
what am i doing wrong?
could someone help me please?