Stealth with multiple opponents

[Sneaky]

Something has been bugging me for a while now, and it's starting to give me some real trouble.
It doesn't seem that skill gains, when succeeding a stealth check against multiple opponents, goes up according to the added difficulty. I'll give an example so people understand what I'm talking about.
I don't remember the exact skill gains as I haven't gottent these high of skill gains from stealth grinding in a long time, so bare with me. Say your stealth roll is 200, and the perception roll of your target is 100. This usually gives you about a .02 skill gain when you are successful, and according to probability the odds of you succeeding are 3/4, that is 3 out of 4 times you will succeed. That's great and all. Now say a second target comes in, now you're rolling your stealth against two rolls, and if you fail either one you get outed. Your probability of succeeding goes down to about 1/2, but you still only get .02. Keep in mind now though that when you go up against a single target with the same odds, that is a target that you have a 1/2 chance in succeeding against you get .04. Throw in the fact that each new entity throws in an extra search roll and your odds start to plunge even more,which makes grinding stealth much harder. It's for these reasons I think that skill gains should be increased with the number of hostile entities in a room. If succeeding against one target would give me .02, then it stands to reason that succeeding against two targets with the same challenge rating would give me twice the skill gain.