For the most part, I race every weekend from April to October, and often twice in one weekend. My weekly training is generally broken down something like this: T/R = train, M/W= active recovery, Sat = train or race, Sun = endurance ride or race, Fri = off the bike recovery. If my weekend race is not an "A-race", then I train through, following the above schedule.
If I have an A-race on sat, I skip the thursday training session, and take that day off the bike. Then do a "pre-race ride", ie a few race pace "openers" on friday. If I have an A-race on sunday, I will either ride easy thurs, or do a 1/2 interval session, take fri off as usual, and do a pre-race ride on sat.
As everyone above said, watch your nutrition and recovery plan, as that can be as important as your training plan - especially if you have back-back races on a weekend! Eat right after a race, feet up, sleep well, avoid alcohol, etc.