I can totally solve this problem but felt that I can learn something by asking a question:
At Seeedstudio, the drill files should have .TXT extension but at OHS Park it's .XLN
I was wondering if the cam processor can generate two identical files one with each extension? 
What I came up was to create another tab to duplicate the existing drill tab in the cam processor, just to teach myself some cam processor stuff. Any problem with this method? Renaming in file explorer works too. I know. Thanks!