In TD, you can set up multiple leagues. It's what I would suggest to you for this instance. You could call one "Tuesday Night" and the other "Friday Night", or what ever would suit you best. Then, when you run the tournaments, make sure that on the game tab, that it's set for the proper league. Then, in stats, you'll want to click on edit profile. From there, you can set up filters that will tally only the tournaments with specific settings. You'll want to create two filters. One that looks at only the Tuesday night league, the other Friday nights. For tournament scoring, you'll want the formula that you have for the tournaments. For overall, if you just want to add them up, the put "sum(scores)". Otherwise, post back here what you'd like to do for the overall scores, and we'll help you out. The players in the database can be a part of any number of leagues, so you don't need to worry about that aspect.
I hope I've been able to help, and as always, if I'm not understanding, please feel free to yell at me