Finding paint colors.....from the can

First off, I would like to say I think I am going to love this section. I recently moved into a new house and I am having fun slowly fixing it up.

So, here's the deal, the inside was recently painted, and they used a flat paint that scuffs up big time wheneevr anything touches it. I have tried a few times to clean the scuff marks, but nothing works. I decided to look through the old paint that the painters left behind so i can just touch up the walls, but the problem is that they didn't mark anything, and all the colors look the same, but in different cans.
The interior of the house has 5 colors, the flat white cieling, the gloss white trim and doors, the eggshell in the kitchen and bathroom, and the beije color which is most of the walls. There are about 10 cans of paint that are all different names, and I believe some are even mixed together to make colors.
So, my question for you guys is..... how the hell can I find out which paint is which without actually going through 10 cans and testing out on a wall? Thanks.