How do you avoid circle jerk repeats with multiple accounts?

I realised that it will be diminsihng returns the more you make. I know you will get SOME repeats but how do you know the majority wont just be the same follwoers form one account to the next if you are targettiing the same niche?

You don't, and frankly I don't see the point of trying to avoid it. After all, you have x better chances of a person seeing your money pins/repins when she is following multiple of your profiles. At least that's how I see it.